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Document:	QMA DMV11 Synchronous Controller User's Guide
Order Number:	EK-DMVQM-UG
Revision:	001
Pages:	172
Original Filename:

OCR Text

EK-DMVQM-UG-001

QMA DMV11
Synchronous Controller
User's Guide

EK-DMVaM-UG-001

QMA DMV11

Synchronous Controller
User's Guide

- Prepared by Educational Services

of
Digital Equipment Corporation

1st Edition, January 1984

The information in this document is subject to change without notice and should not be

construed as a commitment by Digital Equipment Corporation. Digital Equipment
Corporation assumes no responsibility for any errors that may appear in this document.

Printed in U.S.A.

This document was set on a DIGITAL DECset Integrated Publishing System.
e

Class A Computing Devices:

Notice: This equipment generates, uses, and may emit radio frequency energy. The
equipment has been type tested and found to comply with the limits for a Class A
computing device pursuant to Subpart J of Part 15 of FCC Rules, which are designed to
provide reasonable protection against such radio frequency interference when operated
in a commercial environment. Operation of this equipment in a residential area may
cause interference in which case the user at his own expense may be required to take
measures to correct the interference.

The following are trademarks of Digital Equipment Corporation:

EHQHHEHTM

DEC
DECmate
DECset
DECsystem-10
DECSYSTEM-20

DECUS

RSTS

DECwriter

RSX

DIBOL
MASSBUS
PDP
P/OS
Professional

UNIBUS
VAX
VMS
VT

Rainbow

Work Processor

CONTENTS

Page

PREFACE

INTRODUCGTION ...ttt
e e e e e e e e e eee e e e e 1-1
INTRODUCTION TO MULTIPOINT......oooiiiiiiiieee

e, e 1-1

DMV11 GENERAL DESCRIPTION .......ooooiiiiiiiiiieeeeeeeeeeeeeeeeeeeeeeeee 1-1

STANDARD APPLICATIONS ...t
e e e e e, 1-3
DMVI11 SYSTEM OPERATION ......oooiiiiiiii

ee s 1-3

COMMAND/RESPONSE STRUCTURES .........oooiioeeeeeeeeeeeee e, e 1-5
INPUt COMMEANGS ...coiiiiiiiiiiiiiieec e
e e e e e e reaa e 1-5
Output RESPONSES...ccceiiieiiiiiiiiicieeeeeee
e e 1-5

PROTOCOL SUPPORT .....................e
e, e

———————— 1-5

Data MeESSagES....cccoiiiiiiiiiiie sY

CONLrOl MESSAZES. .. .eeeieiieieiiiiiieeiieiee et eeeee e eeeeeeneeeeseeeseneennsens 1=T
MaINtENANCE MESSAZES ....uuvvvrieeeiiiiiieiiiee ettt
e e e e e e e e e e e e e eeseeraaeeeens 1-7

—

Environmental SpecifiCations.............ooovviiiiiiiiiiiieeeeee oo, . 1-7

GENERAL SPECIFICATIONS . ...t
e e e e 1-7
Electrical SpecifiCations ............cccviuviiiiiiiiiiie et
e e e e e 1-8

W ND

0 PXPIIIVRNIAUN
A W

INTRODUCTION

Performance SpeCifiCations ............uveiiiiiiiiiiiiiicie
e
eeaea e 1-8

CHAPTER 2

INSTALLATION

2.1

INTRODUCTION ...ttt
e e e e e e e e e e, 2-1

2.2

UNPACKING AND INSPECTION......coooiiiiiiieeeeee e, 2-1

2.3

INSTALLATION CONSIDERATIONS ..., 2-1

2.4

PREINSTALLATION CONSIDERATIONS . ...ttt 2-1

2.4.1

DevICE PlaCement ..........ouviiiiiiiiiiiiii e 2-5

2.4.2

System REQUITEMENTS........uvvviiiiiiiiiiiiiiiicceeeeeee et
ee
e e e e e e e e eereeas 2-5
INSTALLATION .......oooiov eeteteeeetetetereieerterrnsa——————asoesteteettnererrrrerrrneis 2-9
DMVIIL SYSTEM TESTING ....oooooiiiiiiieeeeeeeee
e
e e e, 2-31

2.5

2.6

2.6.1

Functional Diagnostic TeSting..........eeiviiiiiiiiiiiiiiiieeeeeeeee e 2-31

2.6.2

DEC/X11 System EXEICISET.......ocooiiuiiiiiiiiiiiieieeeeeee
e
eeeee e e e, 2-31

2.6.3

Final Cable Connections .........ccccevvuveveereenennnnn, et
e e et et
at et anans 2-31
DMVIT Link TeStiNg.....ccoooiiiiiiiiiiiiiieeeeeeeeeeeeeeeeeeeee
e
e e e e e, 2-31

2.6.4

CHAPTER 3

COMMAND AND RESPONSE STRUCTURES
INTRODUCTION............e

ettt ettt ettt ———————aaaaeeeeeaeteeeret
. ———————————————————————_ 3-1

Control and Status REGISTErS .....co.uvviiiiiiiiie
e
e e e e 3-1
Input Commands OVEIVIEW........cc.uuvviiiiiiiiiiiee
e 3-5
Output Responses OVEIVIEW..........coocuviiiiiiiiiiieeieeieiieeeee
e eeeeeeeeeeseeeens e 3-5
DMVI11 INPUT COMMANDS ... e
e e e e e e, 3-6
Microprocessor Control/Maintenance Command.............ooceevvveeeveeeereeeeereeennnn.. 3-6

[a—y

—

COMMAND STRUCTURE ........ooiiiiiiie
e
et e e 3-1

WL LW W W W
S

‘p_‘p_‘y—-‘_ay_‘.—-‘p_a_y—‘p—p—‘p-—s._ay—‘p—‘._‘

CHAPTER 1

111

CONTENTS (Cont)

Mode Definition COmmANd .........c.cocuviiiiiiiieiiieiecieeeeteeeereesreesreesseeeeeeeeeeans 3-6
Control ComMmMANd........coovvuiiiiiieeiieiieiiiieee
e e e e ee e
e e eeetreaaeeeeseeeeeeraranenanans 3-9

CHAPTER 4

PROGRAMMING TECHNIQUES

4.1

4.2

4.2.1

4.2.2
4.2.3
4.3

4.3.1

4.3.2
4.3.2.1

4.3.2.2
4.3.3
4.4
4.4.1

442
4.4.3
4.5

4.5.1
4.5.2
4.6

4.6.1
4.6.1.1
4.6.1.2

4.6.2
4.6.2.1
4.6.2.2
4.6.2.3
4.7

4.7.1

4.7.2
4.7.3
4.7.4

4.7.4.1
4.7.4.2

4.7.4.3
4.8

INTRODUCGCTION ... .ccooiiiiiiittiieeie
et ee e e e e e e e e e e e e e e e e e ettt ettt
e s e e e s e e e aaeeaaesans 4-1
COMMAND/RESPONSE DISCIPLINE AND HANDSHAKING..........ccc.cccc.... 4-1
Command DISCIPINE ...ttt
e e eee e et ee e s e e s s e e s seaas 4-2
Retrieving ReESPONSES........ccooiiiiiiiiiiiiiiiiieieeieeiiee
e e 4-3
CSR Interface INteractions ..........ccovviviiiiiiiiiiiiiiiiii i 4-3
DMV LT STARTUP ..ttt
e et reee e eeee e teeeereseeeeeeeeasesseessssssensns 4-3
Configuration Procedure ............coveviiiiiiiiiiiiiiieeiec 4-4
Specifying User-Defined Parameters ........cccocoeeivviieeiiniiieiiniiiiiiiiinee, 4-4
Specifying TSS Parameters .......cccoveeeeeeieiiiiiiiiiiiiiiiiiiiiiecinnieeee 4-6
Specifying GSS Parameters.......cceeveeeeeeiiiiiiiiiiiiiiiiieiicii 4-11
|
ProtoCOl OPEration .........uuuviiriuiiiiierireeeeeeeeeeeeeeeeeeeerereeeeereeeeeeesneienmnnn. 4-13
CRITERIA FOR DETERMINING COMMUNICATIONS LINK
PARAMETERS...ottt
ee e e e e ereeeseeeeseseaneasssenes 4-13
Setting the Selection Interval Timer........ccccoooevciiiiiiiiiiii, 4-14
Setting the Babbling Tributary Timer......ccccoeooiiiiiiiiniiiiiiiiiii, 4-16
Setting the Streaming Tributary Timer.........cccocceiiiiiiiii, 4-16
ERROR COUNTER ACCESS. ... o ittt 4-17
Reading the COUNLErS.......cuiiiiiiiiiieiiiiieeeteeee e 4-17
COUNLET SKEW ..oviiiiiiiiiiieeeeeeetieee
e e e et tiee s e e e eteai e e e eetan e e eeteenaaeseeeearbaassseessann. 4-17
ERROR RECOVERY PROCEDURES......o i 4-17
Recovery from Network Errors...................ett ereeeeear—eeeaeeara——aattraaan 4-18
Recovery from Threshold Errors......... e eeeeeeeeerrar————aaaaaearatraa—aaaaans 4-18
Recovery from Babbling and Streaming Tributary Errors..................... 4-18
Recovery from Procedural Errors.......cccccvveeei, 4-18
Recovery from a Nonexistent Memory Error...............cccoeiinininnnnnnne, 4-18
Recovery from a Receive Buffer Too Small Error........ccccooeeiiiiiiiin 4-19
Recovery from a Queue Overflow Error ...........ccccciiiin., 4-20
BOOTING A REMOTE STATION......uuiiiiiiiiiieee
ettt 4-20
Steps Leading to a Remote Load Detect Boot...........ccccovviiiiiiiiiiiiiiinniinnnn, 4-21
Steps Leading to a Power-On Boot......... et t
ettt ireeeeeeeretara———————aeeeererernran———_, 4-21
Steps Leading to an Invoke Primary MOP Boot ..o, 4-22
DMV11 Switch Settings for the Boot Functions.............occceeeeiiiiiiiiiiiiniiinnnnne 4-22
Switch Settings for the Power-On Boot Function................ccoooeeinnnnne, 4-22
Switch Settings for the Invoke Primary MOP Boot Function................ 4-22
- Switch Settings for the Remote Load Detect, Boot Function.................. 4-23
MAINTENANCE REGISTER EMULATION .....ccccoiiiiiiiiiiiniine, 4-23

3.4.2
3.4.3
3.5

3.4.1

;

Buffer Address/Character Count (BA/CC) Command............cccccveevrrrennnnne. 3-16

DMV 11 OUTPUT RESPONSES ... .ottt 3-18
Buffer Disposition ReSPONSE.........cccuvviiiiiieiiiiiiieeeeeeeeeeee i 3-19
CoNtrol RESPOMSE......uuurriiiiiiieeieiieeiiiitteee
e ererre et 3-20
INfOormation RESPOMNSE........uuuuuuiieiiiiiiiiiiiiiirrirereeeeee
et
reereeeeeeeeeeeeeee s 3-26
TSS/GSS ACCESS. ...ttt
et e e e e e s e srnaase e e e e 3-26

W W W W
LW

R
VS I \§)

Page

CONTENTS (Cont)

Page
CHAPTER 5

ASPECTS OF DMV11 MICROCODE OPERATION
INTRODUCGTION ...ttt
e e e e e e e et eaaeeeeeeeeeeaeenaaaaaeeaes 5-1
DMV11 POLLING ALGORITHM ...ttt
ee e e neeeens 5-1

JAN U A WN—
— 00
SN
-

e
N
w

Determining a Value for DELTA T .....ccoovvviiiiiiiiiiiiiiiieeieeeeeeieeeeeeeeeveeeeeees 5-6
Determining Values for Q and R..........ouoiiiiiiiiiiiiiiiii 5-7
Determining a Value for Poll Delay..........cccccevvvevieiiiiiiiiiiiiiiiiiieiiiieeceeeeeen, 5-8
Determining a Value for DEAD T .......oiiiiiiiiieee
e, 5-8
ERROR COUNTERS.........oe ettt
e e e eeee e e e e e vaeaaeeees 5-8
Data Link Error COUNTerS........oviiiiiiiiieiiiceiiee
ettt eeeeteeeeeeeeeaaeeeeas 5-9
Data Errors Outbound ..........cooouuiiiiiiiiiiiiiee ettt 5-9
Data Errors Inbound............ooovvuiiiiiiiiiiiieee et 5-11
Local Reply TimeEOuULS. ......ccocoieeieiniiiiiiiiiteeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
e ee e
5-11
Remote Reply TImMeEOULS.......cooovvviiiiiiiiiiiiiiieeee
e 5-11
L0Cal BU Er EITOTS...ccuuniiiiiiiieee
ettt
veeeee e e eaees 5-12
Remote Buffer Errors......coooovueiiiiiiieeeeeee
et 5-12
SeleCtion TIMEOULS.......cuuuuiieiiiiiiiiiieeee
et
ettt e e e e e eeeeeenanaas 5-12
Data Messages Transmitted............oouvuvuviiiiiiiiiiiiiiiiiiceeeceeeeeee
eeeeee 5-12
Data Messages ReECEIVEd.......coooeiiiiiiiiiiiiiiiiiiiiicceeieee et 5-12
Selection Intervals................. ett
et eteenttaeeeaetaeentaartaeenaeraaanaararanaren 5-13
Station Error COUNLETS........uvviiiiiieieieiiiiciireeeeeeee
e
5-13
Remote Station EITOIS.......oiiviiiiiiiiiiieeee
et 5-13
L0Cal Station EITOTS ..ouuuniiiiiieee et
e e e e eaes 5-13
Global Header BloCk-Check Errors......coooeiiineeeieieeeieeee
e eeeeeeeeeeeeaenns 5-14
Maintenance Data Field Block-Check Errors .....oovvvvveneevieeieeiiiieeeeeeinnn., 5-14
Threshold Error COUNTETS ......oovvvviiieiiieeeeeeeeeeee
ettt
e e eeeeeeeee e e e eeaeens 5-14
Transmit Threshold EIrors .........oouuueiiiiiiiiiiiiiiieee e 5-14
Receive ThreShold EITOrsS .....ovvvviiieeieee et 5-15
Selection Threshold Errors .......ovvvvvveeeeiiieiiieeeeeeeeeeeee
e 5-15
DMV11 MICROCODE INTERNAL DATA BASE OVERVIEW .........cc........... 5-15
LANKEA LISt .uiiiiiiiiiiiiiieeee
ettt
e et e e e et ee e e e e e eeeeaeeeeeeaeaeees 5-15
The Free LInKed LiSt.......uuoiiiiiiiiiiiiieeee et 5-16
The Response Linked List ........ccoooveiiiiiiiiiiii
e, 5-18
Buffer Linked Lists.........cccvueeveennne.. ett
era et eateer et
era et arraeranas 5-18
Slot Mapping Table............iiiiiiiiiiee
et e e 5-19
TSS and GSS SHIUCLUIES. ....ciiiiiieeieee
et
e eeeee e e e e eeevaeee, 5-19
The Global Status SIot (GSS) ...ooooiiiie
e 5-19
- Tributary Status SIots (TSS) ...coovimiiiiiiiiee
e
e 5-19

DDCMP

DDOCMP ...t e ———— A-1

APPENDIX A

> > > >

()

N
=
L

& BB BB B0 L Lo L0 L L0 L L Lo LY L L L

L LW W W W W

hnhhnhn
.&l\ Lhnhnbhhnhhnhbhnhhnhhbhhhhhhhbhnhhnhhnhnhohnhhnhhnhhnh

Calculating Polling UIZENCY .....ceveiiiiiiiiiiiiiieiieeeceee
et
eee e, 5-2
Criteria for Determining Polling Parameters..........cccvvvvvvvevvvvereenieeieeeeeereeeeeeeeens 5-6

Controlling Data Transfers........cc.vvvvviiiiiiiieieeeeeeeeeee
e
eeeeeee s A-1
Error Checking and ReCOVEIY ......ccoovviiiiiiiiiiiiiiiiiieeeeeeeeeeee
e, A-1
Character COAINE ......coooiviiieeeiiieeeeeee
e e e e e e e e eeeeeaeene A-2

CONTENTS (Cont)

WO DN

> > > >

Page

Data TTANSPATENCY ...couvvrireeeirreeeeieeeeesreeessrteeeessatesstaressssrtesesssresesestreeeensseaanns A-2
Data Channel UtIHZAtion ........cccuviviiiiiviiieieeiiieeeeecireeeeeeeiveeeseesireeeeesssnneeeessenens A2
PROTOCOL DESCRIPTION.......oottttitiiiiiriieieieeeee
e e eeeeeeeeettnteesesiissasss s e e A-2
MESSAGE FORMAT ...ttt
ettt eeeeeeee ettt
s s e e s e e s e e e e eneaes A-4

APPENDIX B

FLOATING DEVICE AND VECTOR ADDRESSES

B.1

FLOATING DEVICE ADDRESSES ......coooooooooooooooeeeeeeeeeeeooeoeeeessssssssssssssssssss B-1

B.3

FLOATING VECTOR ADDRESSES..... oot B-1
EXAMPLES OF DEVICE AND VECTOR ADDRESS ASSIGNMENT ............ B-5

APPENDIX C

MODEM CONTROL REGISTER FORMATS

C.1
C.2

MODEM CONTROL REGISTER FORMATS ..., C-1
RS-449 VERSUS RS-232-C............... etee—ta—.—aaeeeeeeeeeseeeeeeetaeeerrrarrrrrr———aaaaaaeees C-4

APPENDIX D

MODEM CONTROL

MODEM CONTROL ....oooooeeeeeeeeeeeeeeseeeseseoe e seomseseesssesssssasessssensssssesessssessssson D-1
N

B.2

Hardware Modem Control...........ooovviiiiiiiiiiiiieeeree et D-1
Modem Control Implemented by the DMV 11 Microcode..........coocuvieinnnnenn, D-1

APPENDIX E

QMA DMV11 OPTION CONFIGURATIONS

E.1

INTRODUCTION ...ttt
e e e e e e e e eereneeeaanes ORI E-1
OPTION DESIGNATION CONVERSION
...ttt E-1
Factory-Installed System OpPtions .........cccccuuveeeieeiieiniiiiiiiiiiiiiii
e, E-1
Field Upgrade Options.........c.oovvviiiiiiiiiiiiiinineeeeeeeeeeeenececeeeenn, e aaaaa—., E-1
Base OPLions .........ueuvieeieieieeiierieeeeiiiieieen e
e rr—— E-1
CabINEt KItS ..uuiiiiiiiieiiiicieeieee
et
e e e e e e et e e e e e e eeeeenne e e e eeeennens E-1
OPTION CONFIGURATION SUMMARY ..ottt E-1
System Option Designations..........cceeveeriiieriiieeieriiiiiieee
i E-3
Base Option Designations............eeeveuiiiiiieieennieieiieiinneninn,eeeereernirenneenee
e B23
Cabinet Kit DeSIZNatiOns ..........ouvuuiuuiiiiiirreeeeeeeeeeeeeiieeeriiiiiii
e e e e aeeees E-3
DMV11 OPTION CONFIGURATIONS ..otB E-5

E.2
E.2.1

E.2.2
E.2.2.1
E.2.2.2

E.3

E.3.1

E.3.2
E.3.3
E.4

FIGURES

t |"_.| 1 —_——
!
\D 00 ~J O\ 1
W NI »—
N'_"—‘O

wAwRwi-cle
g I n N wnh N whn W

]

[}

DB DLW L LW WWWWWINNMNNMNNNNNNNNNNNDN
— ——

l\)v-—wl\)v-—a\ooo\IO\M-th—‘-r—»—-r—‘r—-\OOO\IO\ul-lkwt\)v—‘wl\)»—-

Figure No.

Title

Page

DMV11s Used in Point-to-Point Applications...........cccccvvvviieiiiiiiiieiiiiieieieeeeeeeeeeeeee, 1-3

DMV11s Used in Multipoint AppliCations ...........ceeeviiiiiviiiiiiiiiiieieeeeeeeeeesseeienneeeenees. 14
General Summary of DMV11 Command/Response Structure..........coocoeevevvvvvvnnnnnnns 1-6
Local NetWork TOpPOLlOZY .....uuuuuuiiiiiiieeeeceee
e 2-2
Remote NEetWOrk TOPOIOZY .....oovvuuiiiiiiiiiieiee
e
e 2-3
MBOS53 SWitCh LOCALIONS......ccoviiiiiiiiieeiiie e e 2-7
MB064 SWitCh LOCAtIONS.....cuvviiiiieii i
e e e e e e e eeeaaraaans 2-8
DMV 11 Switch Selectable Features.........ccoooiviiiiiiiiiiiiiiiiiec e 2-12
Test Connector Insertion
for the M80S53 ... 2-16
Test Connector Insertion for the M8064 ... 2-17
DMV 11 Test CONNECLOTS....ccvvviiiiiiieeeieeiiiiiicieiee
e e e e eeeeeetirrseeeeseeeesereaesaraaeeeeeaeeeeeens 2-18
" DMVI11 Cable Drawings .......cccoocooiiiiiiiiiiiiiiiiiiice
e ereee e 2-22

DMV11 Remote System Cabling Diagram ...........cccooovvvvieeiiiiiiiiiiiineeiiiiiieeeeeeeevianns 2-25
DMV11 to DMVI11 Integral (Local) Modem Cabling Diagram (Point-to-Point)... 2-26
Half-Duplex Multipoint Network (Control Station End Node) ..............cccoveennneenn. 2-27
Full-Duplex Multipoint Network (Control Station End Node)............................... 2-28
Full-Duplex Multipoint Network (Control Station Inner Node) ............................. 2-29
DMV11 CSRs Byte and Word Symbolic Addresses.......cccoeeeeeeeeeeieiiiiiiiiiiiiiiiniiennne, 3-2
Fixed and Variable Formats for Commands and Responses...........ccccccceveeveviivinnnnnn.. 3-2

Microprocessor Control/Maintenance Command Format.........ccoccoevenvieniiiiniencnn. 3-6
Initialization of the DMVI11........cc.cocieniinnnn. et
e e e rae e, e 3-7
Mode Definition Command Format..............ouviiiiiiiiiiiiiiiiiiieeeciee
e 3-8
- Control Command FOrmat...........ouoiiiiiiiiiiiii
e
e e eaeaaes 3-9
Buffer Address/Character Count Command Format...........ccccoovveeeviiiiiiinienniininnnnn, 3-17
Buffer Disposition Response Format............cooooiiiiiiiii
e 3-19
Control-Out Command Format...............ouvuiiiiiiiiiiiiiiiiiiiereee e, 3-26
Information Response FOrmat..........cccovviiieiiiiiiiiiiiiiiiieen
e 3-27
CSR Interface Control BitS.........coooiiiiiiiiiiiie
e 4-2
CSR Access WINdoW..........ueeeeiiiiiiiiiiiiiiiieeeeeeeeeeeee reeeeee
eeee
e aaraia., ....4-4
DMV 11 Maintenance Loop Command Format.............ccccoeeeeiiiiiiiiiiiiiiiiiiieeeeeeeeeee, 4-24
Interrelationship Between Polling Parameters Q, R, and DELTA T........................ 5-3
Relationship Between Polling Parameters Q, R, and the Minimum Polling
|
| 531 0) o7 | USSR 5-4
Relationship Between
the Default Values for Q and R for the Three
|
Polling ACtIVILY LeVEIS ...ouuniiieeiee e
e 5-5
State Diagram of Polling State TransSitions .......cccccoeeevieieeieeeeeeieiiieeieiieeeeeeeeeeeeeeeeenene, 5-7
‘Data Link and Threshold Error Counters..........ccccccooviiiiiiiiiiiiinciiiinie 5-10
STALION B Or COUNTETS . .eeneineie ettt
e e ettt s e st sene et et stneaneennseans 5-11
Data Memory Map.....ccooeveeeiiiiiiieieeeeeee
e, ett ettt
————————— 5-16
DMV 11 Linked List Structure Format.........ccccoooviiiiiiiiiiiiiieeee
e, 5-17
Standard Link BlOCK........cooooiiiii e 5-18
Global Status Slot...........................ett tetttt—t————————————ttatatattaaaaaaeeeaaaaaaaaaiaanrnrarrrarrrnes 5-21

Tributary Status Slot..........e eeeteeeesetbtt————————————————————ttattattatatataaeaeeeeeaaaaaanaaanaraarraans 5-23
DDCMP Data Message Format................. F PSPPI
PP OPPTOOPPN A-1

DDCMP Message Format in Detail.........ccooooiiiiiiiiiiiii
e A-3
UNIBUS and LSI-11 Address Map........oouuuiiiiiiiiiiiieeeeccie e B-2
Flow Diagram Symbology ......cooovvuiiiiiiiiee
e D-4
J\Y CaYe
[ 0 s ML X0 18 o) B (S 1 7: 1 1) FR SRR D-5
Modem Control (TTaANSIMIL) ... .ooivvuiiiiiie
et
e e e e e e e e e e e D-6

Vil

FIGURES (Cont)

Title

Page

Modem Control (Transmit 2).......cccccoviiiiiiiiiiiniiiii
e D-7
Modem Control (Receive).....cceeeeveveevvnnnneee. ett
———tett et e et e e rra——ararnns e D-8
Modem Control (Modem Status)......cccceeeeeeeeennnn. e
e ee et ———eeettti et ettr——eeerraas D-9
Modem Control (Call TIMET) ......uuuuuueueeiiiiniiiiiiriereeerrirrrrreereereerereerreeereeeteesiieereee D-10
Modem Control (Shutdown).........oevvviiiiiiiiiiiiieriereeeeeeeeeeeeeeeeeeeeeres eeeeaees D-11
System Option Designation ...........cccccevvriiieiiiiiiiiiiiiiiii
e E-3
Base Option DeSignation...........cccvivriieiiiirieeeiiiiiiieeeeniiieeet e E-3
Cabinet Kit Desination ...........ceeiieiiiieiiiiiiiiiiiiietteeeee
e eeeserriirssteeree s e s s s sssasssarraaaeeees E-4

TABLES

palles

B [\

NS —

i Tl & © ® AUV P WN=—=OOIOAWMPE
WN =00 IO W S W

S PRABRARPBAEPRAULWWWWLWWLWUWLWUWWNNDINDNDDNDDND

Title

Page

DMV
11 OPLIONS ..uvuurrenirrnriieiuruerireereeereeeeeereeereeereeressesresiisteteetrerttetresese e 1-2
Typical Host Options of a Bell 208ATM Data Set (4800 b/s) Full-Duplex
100753
7215 e] 1 LSOO
OO PP PP PP P 2-4
Typical Tributary Optlons of a Bell 208 ATM Data Set (4800 b/s) Full-Duplex
(@073
- 14 (o) ¢ KU U
U OO 2-4
DMV 11 Voltage CRart......ccoviiiiiiieiieiieeeeetee ettt 2-6
Device AdAress SEIECTION .....oviiiiiiiiiiiiieeee
et
e ee et e e e eeeteereeee s eeeeraaanaaaes 2-10
Vector AdAress SElECION. ... ..cvviiiiiiiiiiiiiiee e e eeeeriiree e e e eertereee e e e eeeerernrasseseeessraanas 2-11
DMV11 E101 (M8064)/E107 (M8053) Switch Selectable Features .....ccooeeevvvnnnn.. 2-13
CaADINEt KItS . iiiieeiiiiiiiiieieee
et e et e e e e e et e e s e eaaba e e e eereenaa s e esananaseens S 2-15
Switch Function Settings on 70-20863 Panel for RS-232-C Interface ................... 2-30
SELOD Bit FUNCLIONS ...uviiiiiiiiiiee et e et e st e eeeeseetenas s e tbanesesnaa s e e naaans 3-2
BSEL?2 Bit Functions.............cccc....... ett
et —eaeeeert——teeertta——aaaarata—eatetaa
eeeaanaans 3-4
Input Command Codes............oociiiiieiiiiiiiieiiiiie
s 3-5
Mode Field Codes and Functions..........ccccooeveiiiiiiiienneeeceeeeeienen
e, e raana. 3-8
SEL6 Control Command FUNCHONS...........coeiiiiiiiiiieiiieiiiee
et 3-10
Request Key Field Definitions (Control Command)...........cccoeviiiiiiiiiniiiiniennnnn, 3-14
Output Codes (BSELD) ......ocoiiiiiiiiiiiiiiiiiieeeeie it 3-21
Return Keys for Information RESPONSE .......ccceeeerieiiiiiiiiiiiiiiiiiiiiiiniieee
e, 3-27
Diagnostic Error Codes .......cceeeveviieeinniireiiniiieeiiicniiiccenineec
e ererrrer————————————— 4-5

User-Defined TSS Parameters .........cccccveeveevenen.. ee
————— e s oa—reeenarese 47

User-Defined GSS Parameters ........uuuvveiiieeeiieriiieieeeeeiiiiieeee e eeeennenanaaaes 4-12
Recommended Selection Interval Timer Values........cveeriiiiiiiiiiiciiiiiiiii, 4-15
Mode SWILCh SEttINES ...uvvvvriieieiiiiiiiiiii
bbb anaes 4-23
Maintenance Command Functions BSEL2 Bits 0-3 ............ ot tee e e e ——————————aaean, 4-25
Floating CSR Address DEVICES .......ccvevveriirienieeieienieeienecresre ettt B-3
Floating Interrupt Vector Devices..........et eeeertereraeeetebt——aaaeera—aeeeerea
e eeranaseeans .B-3
- DMV11 Modem Control Functions ...........cccccccevvieiiiiciiinnnnnes et
et e ettt D-2
-~ Option Compatibility Cross-Reference.........cccccooevviiiiiiiiiiiiiiiii
s E-2
Electrical and Mechanical Interface Type .....couuoeiiieiiiiiiiiiiii
e, E-3
e e e s e e e e aaaaaaaeans E-4
Cabinet Kit COMPONENTS .....ceeiiiiiiieiiiieieiiiieieerereer e e e
DMV 11 Option Configurations.............ceeeeeeeeeeeereiiiiiiiiiiiiiiiiiiiiireeeee
e eee e E-5
V1il

PREFACE

The Qualified Modular Assembly (QMA) DMV11 Synchronous Controller has been tested and meets all
requirements for limiting electromagnetic interference.

This manual has been written to meet the needs of Field Service personnel and contains the following
categories of information:

General description including features, speéifications, and functional descriptions,

[Installation,

(Command and response structures,

Programming, and

Microcode operation.

This manual also includes appendices that discuss DDCMP, floating device and vector addresses, modem
control register formats, modem control, and the QMA DMV11 options and cabinet Kkits.
NOTE
In this manual, the QMA DMYV11 Synchronous
Controller is referred to as the DMV11 for brevity.

CHAPTER 1

INTRODUCTION

1.1

INTRODUCTION

The multipoint DDCMP-DMV 11 Intelligent Communications Synchronous Line Controller is a device
which provides efficient high-speed synchronous communications for distributed networks. The DMV11

uses LSI-11 CPUs as control or tributary stations, while requiringa minimum of main CPU resources.
This manual provides detailed information necessary for installing and operating the DMV11.
1.2

INTRODUCTION TO MULTIPOINT

Point-to-point configurations are practical when the message rate of the terminals is high. In many cases,

however, the message rate of the terminals is very low even though the bit rate may be quite high. In these
cases, sharing a transmission line can significantly reduce the cost and improve the efficiency of a
communications network.

/’\

Various techniques are used to share transmission lines to improve their utilization. One of these techniques is the use of multipoint lines. In multipoint operation, a single line can be shared among many
nodes. Each node is a station and has a unique address. One station in the network is always designated as
the control station while the remaining stations are designated as tributary stations. Because all stations are
connected to the same line, no two tributary stations may transmit at the same time, and each station must
have a means of recognizing which messages it is meant to receive. The address field of the message
header identifies the staion to receive the message. The control station governs sharing of the line by means

of polling in order to authorize transmission to the control station. In a polling operation the tributaries are
in effect asked one by one whether they have anything to transmit. To accomplish this, the control station
sends a polling message with a unique tributary address down the line. The station Wthh recognlzes the
address responds by sending data or by sending a positive response.

Tributary stations can only transmit to the control station and only in response to a polling message from

the control station. Transmission between tributaries is not allowed as all message traffic must be routed
through the control station. Control stations on the other hand may transmit to any tributary at any time if
the communicating stations are in full-duplex. In fact, multiple messages for different destinations
(tributaries) can be sent serially by the control station. Each tributary station then, in turn, examines the
address and accepts only those messages it is meant to receive.
The use of communication lines can be maximized by using full-duplex capabilities at the control station to
accommodate many tributary stations on a full-duplex line. In this mode, the control station keeps the lines
full by sending to one or more tributary stations, while at the same time receiving from another tributary
station.

P
Ve

’\\ N

1.3
DMV11 GENERAL DESCRIPTION
The DMV
11 is a high-performance line controller which operates at speeds up to 56K b/s. It accomplishes
this by doing DMA transfers.
The available options are listed in Table 1-1.

1-1

Table 1-1

System Option

Base Option and
Cabinet Kit for

DesignationTM®

Field Upgradet

DMVI11-AP

DMV11-M

+CK-DMV11-Ax
DMV11-BP

Line Speed

EIA RS-232-C

Up to 19.2K b/s

CCITT V.35

Up to 56K b/s

Integral modem

56K b/s only

DMV11-N

+CK-DMV11-Cx

DMV 11-FP

Interface

DMVI11-M

+CK-DMV11-Bx
DMV11-CP

DMV11 Options

DMV11-M

+CK-DMV11-Fx

|
EIA RS-423-A/449

Up to 56K b/s

*Letter P indicatesAfactory-installed system option. Refer to Appendix E, Table E-1, for old/new option
designation cross-reference (that is, non-FCC compliant/FCC compliant).
tx = A, B, or C, as applicable.

Features of the DMVII include:

. Suppdrt of point-to-point and multipoint operation,
e

Support for remote or local, full-duplex, or half-duplex cofifigurations,

Support for 12 tributaries and‘one. control station in multipoint operation,

Switch and program selectable operating mode and tributary address,

Support for multiple addressed tributaries,

Down-line loading and remote load detect capabilities,

Go/No-Go diagnostic teSting by the microcode,

Go/No-Go extensive error reporting,

Modem control.

1.4

STANDARD APPLICATIONS

The DMVI11 can be used with the integral modem as well as with EIA and CCITT applications. These
applications can be configured as either point-to-point or multipoint networks. Figure 1-1 shows a typical
point-to-point application and Figure 1-2 shows a typical multipoint application. For local operations

through integral modems, stations are interconnected by twinax or triaxial cables. The integral modem can
support up to 12 drops in both half- and full-duplex modes. For remote operations, stations are connected

through external modems that use common carrier facilities. For specific information on installation of
either of the basic DMV11 units and associated options, refer to Chapter 2.

LSI-11 CPU

LOCAL

OPERATING
SYSTEM

LSI-11 CPU

NODE

OPERATING

’

SYSTEM

USER PROGRAM

REMO TE

NODE

USER PROGRAM

DEVICE DRIVER

LSI-11 BUS

DEVICE DRIVER

LSI-11 BUS

4
#1

TRIB.

—

:
NOT

——

USED

= ="

|
>
MODEM I
€
b

‘

— — J

r=——- -TI
.
<
7’-——-»: MODEM [«—>

DMV11

Lo —

#12

DMV11

MK-2485

Figure 1-1

DMV11s Used in Point-to-Point Applications

For multipoint applications, the tributary address for each DMV11 in the network is either switch or

program assigned. In the case of switch-assigned tributary addresses, specific switches on each DMV11

define the numerical value of the address to which that DMV11 responds. The advantage of a switch-

assigned tributary address is that it provides data transfer security since the address cannot be changed by
software.

A major adVantage of DMV 11 multipoint networks is the ability of the main CPU at the control station to
down-line load programs to the CPU at each tributary and start those programs without manual intervention. As a result, DMV11-based multipoint networks are particularly suited for installation at remote and
generally inaccessible locations. For example, DMV11s may be used in remote systems, in hard to reach
locations such as weather stations at sea, and in hazardous environments.
1.5

DMYV11 SYSTEM OPERATION

Operation of the DMV11 communications line controller is initiated and directed by a user program
residing in the main memory. The user program consists of an application program and a device driver
that serves as an interface between the DMV11 and the CPU.
Communication between the user program and the DMV11 is accomplished over the LSI-11 bus through

four control and status registers (CSRs). These four 16-bit registers serve as a bidirectional port to pass
user-program commands to the DMV11, and DMV11 responses to those commands back to the user
program. Each of these registers are word and byte addressable by both the user program and the DMV11
microcode.

1-3

TNYO.NIYLIVI1NSI) |v#,#_€E# vetWIGLOW!

1-4

W31SAS

13S 'gid1

- r

L
11-IST SN

—

— \

W3LSAS

3aON O

$S34aAvILINW

S101S HO4

L1-1ST sNa

TOULNOD|z# ,.\_.Z_On:.._:s_SNLV1S1O1S o—_ \H3NsOnIL/VWLVLSHNOI0OUddILINW|

L1-IST sSNg

Lv(13IiuAvnaWiGonyLs|]—e¢—l:T#% { —ASHN-VL|LV—NL[GSISYLLO1S
|L3AAOWNGv HaO4Wr3HAOLOIWMS| U ONILYHIdO
HIDIISAN3A/N"3VIHAOIY0AHd Li-IsT SNy H3IISAN3d/IHN3VAHIOH0AHd
301A30 43AIHA

LONILVH3IdO
L-I1S1 Ndd
W31SAS

3gAON

ONILVH3dO W3LSAS

ONILVH3dO0

hec———

[anumN

‘

NOTE
Normally only four CSRs are available to the user
program. However, in 22-bit address mode, eight
CSRs are available although only one additional 16bit register is used.

In this group of four CSRs, the first two have a fixed format and in general serve as a handshake control
for user-program commands and DMV 11 responses. The next two CSRs form a port for the exchange of
commands and responses between the user program and the DMV11. Other control fields provide for
initialization, interrupt enabling, reading and execution of maintenance instructions, data transfer setup,
and tributary addressing.
A user program issues a command to the DMV11 by first requesting the use of the data port. When the
DMV 11 grants permission to use the data port, the user program passes the command to the DMVI11 in
the CSRs. The DMV11 interprets the command and performs the specified actions. If a response is
required, the DMV 11 stores the appropriate response in the CSRs and then 1nforms the user program that
a response is present.

Message data received or to be transmitted by the DMV11 is written into or read from preassigned buffers
in main CPU memory. These buffers are accessed by the DMV11 through nonprocessor requests (NPRs)
to the associated bus address.
1.6 COMMAND/RESPONSE STRUCTURES
Since the DMV11 is basically an input/output device, it follows that the command/response set for this
device be categorized as input commands and output responses. Input commands are commands issued by
the user program to the DMV11. Output responses are typically responses to those commands, and are
issued by the DMV11 to the user program.

Some responses are unsolicited, and are used to inform the user program of protocol events and line errors.
1.6.1

Input Commands

There are four types of input commands. They are listed belowin the usual order of issuance.
1.
2.
3.
4.

Microprocessor control/ maintenance,
Mode definition,
Control,
|
Buffer address/character count.

1.6.2 Output Responses

Output responses serve to inform the user program of normal or abnormal conditions concerning the data
transfer operation. There are three types of output responses:
1.
2.

Control response,
Information response,

Buffer disposition response.

Figure 1-3 is a general summary of the functions performed by the DMV11 command/response structure.
These commands and responses are discussed in detail in Chapter 3.
1.7 PROTOCOL SUPPORT
In DMV 11 point-to-point and multipoint networks, all message transfers between nodes are under control
of the Digital Data Communications Message Protocol (DDCMP). All aspects of DDCMP processing are
handled by the DMV11 microcode. Message handling at the user-program level only involves setting up
data buffers during transmit operations and accepting data from the DMV11 during receive operations.

1-5

LSI-11

USER PROGRAM

USER PROGRAM ISSUES
MICROPROCESSOR CONTROL

INITIALIZE

COMMAND TO MASTER

DMV11

CLEAR DMV11

NOTIFY

| FAILURE

USER

PROG. VERIFIES

INTERNAL

PROGRAM

DIAG.

SUCCESSFUL
DMV11 RUNNING
SET MODE OF HALF=-

OR FULL-DUPLEX,

ESTABLISH STATION

USER PROGRAM ISSUES

AS POINT-TO-POINT

MODE DEFINITION

NODE OR MULTIPOINT

COMMAND

CONTROL OR TRIBUTARY
STATION

Y
ESTABLISH TRIBUTARIES,

SET USER DEFINED

USER PROGRAM ISSUES

PARAMETERS, INITIATE

CONTROL COMMANDS

PROTOCOL STARTUP

ASSIGN TRANSMIT
AND

RECEIVE BUFFERS

TRANSMIT

USER PROGRAM ISSUES

BUFFER ADDRESS /
CHARACTER COUNT

COMMANDS

RECEIVE

{

{
THE DMV11

THE DMV11 PERFORMS THE FOLLOWING

PERFORMS THE FOLLOWING

RECEIVE MESSAGE FUNCTIONS:

TRANSMIT MESSAGE FUNCTIONS:

1. PROCESS RECEIVE HEADERS

1. CREATE DDCMP MESSAGE

HEADERS

2. CHECK CRC’s

3. ACKNOWLEDGE (ACK) PROPERLY

2. GENERATE MESSAGE AND

RECEIVED MESSAGES
4, NEGATIVE ACKNOWLEDGE (NAK)

HEADER CRCs

3. TRANSMIT MESSAGES

ERRONEOUSLY RECEIVED MESSAGES

y
THE DMV11 PERFORMS THE FOLLOWING
MESSAGE TRAFFIC CONTROL FUNCTIONS:
1. MESSAGE SEQUENCING
2. ERROR RECORDING AND REPORTING
3. PROTOCOL SUPPORT

DMV171 ISSUES BUFFER
DISPOSITION RESPONSES,

CONTROL RESPONSES AND
INFORMATION RESPONSES

4. LINK MANAGEMENT
MK-2651

Figure 1-3

General Summary of DMV11 Command/Response Structure
1-6

There are no file structure constraints on messages transmitted or received over DMV11 networks;
however, the maximum data message length allowed is 16,383 bytes. Also, there are no restrictions as to

the type of data transmitted or received under DDCMP since all data is transmitted and received in
transparent form.
There are basically three types of DDCMP messages: the data message, the control message, and the
maintenance message (refer also to Appendix A for additional information on DDCMP).

1.7.1

Data Messages

DDCMP data messages consist of two parts: the message header and the message body. The header
consists of eight bytes of control information necessary for successful transmission of the message.
Included in these eight bytes is the block-check count (BCC) for the header, the byte count of the message
body, and the tributary address. The header also contains two control bits; one that indicates resynchronization after this message, and one that controls line turnaround. The message body consists of the
message and a BCC for the message. Both BCC characters are used by the DMV11 to validate messages
as they are received.
The header is assembled by the DMV11 and transmitted with the message body to form the data message.

The receiving DMV11 uses the header to verify the address and ensure that the message is received in the
correct sequence. The header is also used to determine the number of bytes to transfer to the user

program. The header is discarded when the message is successfully passed to the user program.
1.7.2

Control Messages

Control messages are used to manage message traffic. They are eight-byte DDCMP messages which are
passed between control and tributary stations under sole control of the DMV11. Two examples of control

messages are acknowledge (ACK) and negative acknowledge (NAK). ACKs indicate successful reception
of messages while NAKs indicate unsuccessful reception. Control messages in multipoint also contain the

address field to identify the tributary to which the message is sent or received from.
1.7.3

Maintenance Messages

Under DDCMP, a DMV11 has two data transfer modes: the DDCMP run state, and the DDCMP
maintenance state. In the run state, a DMV11 receives and transmits data messages. In the maintenance
state, a DMV 11 receives and transmits onl/y maintenance messages. A maintenance message is formatted
much like a data message. It is formed by an eight-byte header followed by a variable length message
body. The content of the body is determined by the user program. Maintenance messages may consist of:

1) operating or diagnostic programs transmitted by the control station for down-line loading into the CPU
of a specified tributary, or 2) a portion of the contents of a tributary’s CPU memory as requested by the
control station. The request of this information is also handled by a maintenance message.

1.8

GENERAL SPECIFICATIONS

Environmental, electrical, and performance specifications for all DMV11 configurations are listed in

Sections 1.8.1 through 1.8.3.
1.8.1

Environmental Specifications

The DMV11 is designed to operate in a class C environment as specified by

DEC STD 102 (extended).

Operating Temperature

5°C (41°F) to 50°C (122°F)

—

ARelative Humidity

10% to 90% with a maximum wet bulb temperature of 28°C (82°F) and a minimum dew point

2°C (36°F).

1.8.2

Electrical Specifications

The DMV11 requires the following voltages from the LSI-11 bus for proper operation.
Option

Voltage

DMV11-AP, BP, FP
A

+5V@4TlA
+12 V @ 0.380 A

DMV11-CP

+5V @44 A
+12 V @ 0.260 A

A —12 V @ 250 mA required by the level conversion logic for both versions is generated off the +12 V by
a switching inverter.

1.8.3 Performance Specifications
Performance parameters are as follows:

—

Operating mode

- Full- or half-duplex

—

Data format

Synchronous D’DCMP

—

Data rates

Up to 56K b/s

—

Tributaries supported

Up to 12

DMVI1ls may be connected to DMP11s/DMV11ls, DMR11s, DMCl1s, and any other synchronous
controller running DDCMP protocol.

1-8

- CHAPTER 2
INSTALLATION

2.1

INTRODUCTION

This chapter provides all the information necessary for a successful installation and subsequent checkout
~of the DMV11. Included are instructions for unpacking and inspection, preinstallation, installation, and
verification of operation.

2.2

UNPACKING AND INSPECTION

The DMV11 is packaged according to commercial packing practices. When unpacking, remove all
packing material and check the equipment against the packing list. Inspect all parts and carefully inspect
the module for cracks, loose components, and separations in the etched paths. Report damages or
shortages to the shipper and notify the DIGITAL representative.
2.3 INSTALLATION CONSIDERATIONS
Installation of the DMV11 microcontroller/line unit subsystem should be done in three phases:

Phase 1 — Preinstallation considerations
Verify system requirements, system placement, and configuration requirements.
Network topology chart

For multipoint networks it is absolutely necessary to know the configuration of the DMV11]
(that is; control tributary, HDX, FDX, and so on) locations of tributaries (w/address), and
- where in the network they are connected (control, Trib 187, Trib 98, Trib 208) or else
troubleshooting will be extremely difficult.
e

Phase Il — Microcontroller/line unit installation

Configure, install, and verify the microcontroller/line unit module via the appropriate
diagnostics.

Phase III - DMVII system testing
Verify the DMV11 microprocessor subsystem operation with the functional diagnostics and
system exerciser programs.

2.4

PREINSTALLATION CONSIDERATIONS

The following should be considered prior to ordering a DMV11 communications interface to ensure that
the system can accept the DMV11 and that it can be installed correctly. The steps should also be verified
at installation time.

It is strongly recommended that a topology diagram be drawn at installation time and maintained
throughout the life of the installation. Figure 2-1 shows a local network topology and Figure 2-2 shows a
remote network topology.

2-1

ELEVATOR SHAFT

RX | TX
DELTA

11/70
DMP11

TRIB 3
RSTS XX.X

DE - XX.X

SUSPENDED CEILING

ROOM 515

RX | TX

J
I

|
1 Y

[

BETA

DMV 11

DMP 11

TRIB 2

TRIB 1

RSX 11M

RSX11 M

DM - XXX

DM - XX.X

RX | TX
GAMA
11/23

11/34

ROOM 412

ROOM 430

—

RX |

ALPHA

VAX 11/780
DMP 11

CONTROL
VMS XX.X

DV - XX.X
ROOM 111

MK-2502

Figure 2-1

Local Network Topology

2-2

MERRIMACK
VAX 11/780
VAX VMS XX.X

DV-XX.X

*NOTE
1
*NOTE3
CONTROL

*NOTE1
PATCH PANELS ARE

NASHUA

RECOMMENDED BUT MAY

NOT ALWAYS BE USED.IFTHEY
ARE USED, THEIR PHYSICAL

4800 | NASHUA

LOCATION SHOULD BE

IEXCHANGE

INDICATED.

4800 fl

11/60
RSTS XX.X
DE-XX.X

1
*NOTE
3
*NOTE

2
* NOTE

TRIB 1

MODEM - 208A

CONTROL STATION OPTIONS
SEE TABLE 2-1

3
*NOTE

TEWKSBURY

MODEM - 208A
TRIBUTARY OPTIONS

LOWELL

SEE TABLE 2-2

EXCHANGE

VAX 11/750
VAX VMS XX.X
DV-XX.X

*NOTE1
3
*NOTE
TRIB 2

4800

I MAYNARD I 4800
IEXCHANGEI

MARLBORO

4800

11/23
RSX-11M
V.3.2

.
DM XX.X

1*NOTE
2
*NOTE

MARLBORO
EXCHANGE

MAYNARD

11/23
RSX-11M

TRIB 4

V.3.2

1
*NOTE
TRIB 3

MK-2648

Figure 2-2

Remote Network Topology

2-3

Typical Host Options of a Bell 208ATM Data Set (4800 b/s)

Table 2-1

Full-Duplex Operation

" DEC Recommended Settings

Data Set Options

Transmitter timing

Switched

Carrier control

Data set (internal)

Request-to-send operation in

Switched

One second holdover at

Not provided

continuous carrier mode

receiver on line dropouts

New sync-option to squelch
receiver clock

Not used — NS is strapped OFF

within the data set

CC is ON when the AL button (only)

- Data set ready lead option

for analog loopback testing

is depressed

by data terminal

r /_——«'\\

Bell 208ATM is a trademark of Western Electric.

Table 2-2

Typical Tributary Options of a Bell 208ATM Data Set (4800 b/s)
|

Full-Duplex Operation

Data Set Options

DEC Recommended Settings

Transmitter timing

Data set (internal)

Carrier control

Switched (48.5 ms CA-CB delay)

Request-to-send operation 1in
continuous carrier mode

Switched (8 ms .5 CA-CB delay; 0-35
ms depending on distance) N/A

One second holdover at

receiver on line dropouts

Ndot provided

New sync-option to squelch
receiver clock
|

Not used — NS is strapped OFF
within the data set

Data set ready lead option

CC is ON when the AL button (only)

for analog loopback testing

is depressed

by data terminal

2-4

The topology diagram should provide the following information.

Cable routing -

Show the actual physical location of the cable trough and
indicate any equipment which might cause interference
such as an X-ray room.

Machine type —

Indicate whether the CPU is a PDP-11/23, PDP-11/70,
PDP-11/34, VAX-11/780, and so forth. (The network
could consist of a mixture of DMP11s and DMV 15s).

Type of station -

Indicate if the station is a control or tributary station.

- Physical address -

DDCMP address can range from 1-255.

Location -

Indicate by room number or other appropriate means, the
actual physical location of the equipment.

Node name -

The name given to the tributary if applicable.

Operating system and
version —

The name of the software operating system such as RSX11M V3.2.

DECnet version -

- DECnet software version such as DECnet-11M V3.0.

Transmit and receive -

Show transmit and receive lines. Depict end nodes and
show termination. If a patch panel is used, indicate the
line numbers between patch panels.

- NOTE
The use of patch panels and numbering of the lines is
recommended.

2.4.1

Device Placement

The DMVI11 can be installed in any LSI-11 bus-compatible backplane such as H9276. On systems that
contain many high-speed direct memory access (DMA) devices, there is a probability of adverse bus

latency. To help prevent against this occurrence, the DMV11 should be placed physically close to the
processor. As a result, this gives the DMV11 a high DMA priority.

2.4.2

System Requirements

LSI-11 bus loading

The M8053-MA or M8064-MA present two ac loads and oné dc load to the LSI-11 bus.
®

Power requirements

Check the power supply before and after installing the microcontroller/line unit to ensure
against overloading. Power requirements are listed in Table 2-3.
®

Interrupt priority

The interrupt priority is preset to level four.

Device address assignment

The DMV11 address resides in the floating address space of the LSI-11 bus addresses. The

ranking assignment of the DMV11 for bus addressis 24. (See Appendix B to determine the
proper bus address.)

The selection of the device address is accomplished by switchpacks on the microcontroller/line
unit module. Refer to Figures 2-3 and 2-4.

Device vector address assignment

The DMV11 vectors reside in the floating vector space of the LSI-11 bus addresses. The
ranking assignment of the DMV11 for vector assignments is 46. (See Appendix B.)

The selection of the vector address is accomplished by' a switchpack on the microcontroller/line
unit module. Refer to Figures 2-3 and 2-4.

Table 2-3

DMV11 Voltage Chart

Maximum

Minimum

Backplane

+35.0
+11.40

AA2
AD2

+5.0

AA2

Voltage

Module

Voltage Rating

M8053-MA

+5V @47 A
+12 V@ 0.380 A

+5.25
+12.60

M8064-MA

+5V @ 4.4 A

+5.25

AD2

/""\

+12.60

- +11.40

+12 V @ 0.260 A

Voltage

2-6

M8053

[

N
MK-2698

Figure 2-3

M8053 Switch Locations

21N

‘%

——]

M8064

I I
Figure 2-4

|A
MB8064 Switch Locations

2-8

B
MK-2521

(

2.5

INSTALLATION

“When installing the DMV11 in the LSI-11 bus-compatible backplane, LSI-11 configuring rules must be
followed.

Proceed with the installation as follows by performing the following on the slot that will contain the
DMV11.
1.

Verify that the backplane voltages are within the tolerances specified in Table 2-3.

Turn system power OFF and perform resistance checks on the backplane voltage sources to
ground. This ensures that no short circuits exist. Refer to Table 2-3 for backplane pin

assignments.

Configure the correct device address (as determined from Appendix B) using switchpack
settings from Table 2-4.

Configure the correct vector address (as determined from Appendix B) using switchpack
settings from Table 2-5.
|

Verify that the switch selectable features of the DMVI11 are configured for the station being
installed. See Figure 2-5 and Tables 2-6 and 4-3.

Insert the appropriate module test connector into the correct microcontroller/line unit connector as specified in Table 2-7. Be sure to insert the test connector with “SIDE 1" (etched on the
test connector) visible from the component side of the module. Refer to Figures 2-6 and 2-7.

Schematics and outline drawings of each test connector used with the DMV11 are provided in

W-

Figure 2-8.
7.

Install the DMVI11.

Turn system power ON.

Load and execute the DMV11 static diagnostics. Five error-free passes of each part 1s the
minimum for successful operation.
(CO)VDMA** — DMV 11 static logic test part 1
(CO)VDMB** — DMV 11 static logic test part 2
(COVDMC** — DMV 11 static logic test part 3
(CO)VDMD** — DMV11 static logic test part 4
(OVDME** — DMV 11 static logic test part 5

10.

Remove the module turnaround test connector and connect the appropriate cable (see Table 2-7
and Figure 2-9) to the proper BergTM connector for the DMV 11 option selected. Refer to Table
2-7 for detailed information on cable requirements and to Figures 2-10 through 2-14 for system
cabling configurations.
NOTE
|
When installing panel cables 70-20862, 70-20863,
or 70-20864, it is important that the panel be properly mounted to the rear-mounting bulkhead to

ensure adequate grounding.

BergTM is a trademark of Berg Electronics.

When connecting the 70-20863 connector panel, verify that the appropriate modem switches on
the panel are properly configured for the option selected. Table 2-8 lists each of these options and required switch configurations.

Integral modem options require that a 75 ohms terminator be connected to each receive line
(70-20862 panel) at each end of a full-duplex and a half-duplex network. Refer to Figure 2-10
for DMV11 remote cabling and to Figure 2-11 for DMV11 to DMV11 local cabling.
11.

Insert the appropriate cable turnaround test connector in the end of the cable. Refer to Table 27 for the specific test connector. Load and execute the static diagnostics specified in Step 9
using the external maintenance mode selected to verify the module and cable. Upon obtaining a
minimum of five error-free passes, proceed to the DMV11 system test procedures, Section 2.6.
Figure 2-8 illustrates the various test connectors used in the DMVI11.

Table 2-4

Device Address Selection

MS B

LSB

15[1 4|13
1

12]11

NUMBER

9[8

615

| <————— M8053 E53 M8064
E 58

y o,|

SWITCH

4
»

MB8053
E54

1 | o
o]

b
M8064|
||I=|E59I

s8 | s71s6|

s5]s4]s3|s2)

s1]s2]

ON | ON
ON

"DEVICE

ADDRESS

760020

760040

760060
760100

760200

ON | ON

760300

760400

ON
ON
ON | ON
oN | oN | ON

760500
760600
760700

3[2

761000

762000

ON | ON

763000

764000

NOTE: SWITCH ON RESPONDS TO LOGICAL ONE ON THE BUS
MK-2564

2-10

‘Table 2-5
‘MSB

]

Vector Address Selection
|

|15]14

12]11

9[8

[ol ol

olo

o]‘

8053 E6d

[1/0

M8064 E59

’ .'

SWITCH

NUMBER

6[5

312

LSB

1 | o

S8 | S7 | S6

S5 | S4 ] S3

oN | oN
oN | on

oN | on
ON
oN | oN
oN | oN
ON | ON | ON
oN | on | ON
ON
on | on | on | oN
ON

on | onlon | on ]| onN

VECTOR

ADDRESS
300
310

320
330
340

350

360
370
400

500

ON | ON

600

on | on | ON

700

NOTE: SWITCH ON PRODUCES LOGICAL ONE ON BUS
MK-25683

2-11

' DDCMP ADDRESS REGISTER
~

TRIBUTARY/PASSWORD

E 119 (M8064)

OFF = ONE

E 113 (M8053)

MODE

UNIT

AUTO

POWER

REMOTE

MODE WHEN

ENABLE

NUMBER

ANSWER

LOAD

SWITCH ONE

IS SET

FOR

BOOT

DETECT

BOOTING

ENABLE

E 107 (M8064)

OFF = ONE

E101 (M8053)

SWITCH SETTING FOR THE MODE OF OPERATION.

ON | ON | ON

HDX PT TO PT DMC COMPATIBLE

OFF | ON

FDX PT TO PT DMC COMPATIBLE

ON | OFF | ON

HDX POINT TO POINT

OFF | OFF | ON

FDX POINT TO POINT

OFF

HDX CONTROL STATION

OFF | ON

OFF

FDX CONTROL STATION

OFF

HDX TRIBUTARY STATION

OFF| OFF

OFF

FDX TRIBUTARY STATION

HIGH SPEED SWITCH

MUST BE SET

FOR INTEGRAL
MODEM OR WHEN

HIGH

“ON” = V.35

SPEED

"OFF’ = EIA

RUNNING ABOVE 19.2KB

* UNUSED

M8053

E 107 (M8064)

E 101 (M8053)

OFF = "LOGIC ONE"

M8064

OFF = ONE
MK-2493

Figure 2-5

DMV11 Switch Selectable Features

2-12

Table 2-6

DMV11 E101 (M8064)/E107 (M8053) Switch Selectable Features

~ Switch Peosition

DMV11 Function/Description
when Switch is Enabled

Switch

when Function

Number

Name

'is Enabled

MODE ENABLE

OFF

Indicates that the DMV11 mode of operation is defined in switches 6, 7, and 8. If
disabled, mode of operation must be
software assigned.

UNIT NUMBER
FOR BOOTING

ON or OFF

Defines which DMV11 is performing the
remote boot if two DMVI11 options are
installed on the same LSI-11 bus. This
switch offers the selection of:
Unit Number Zero = “ON”
Unit Number One = “OFF”

OFF

Causes the DMV11 to assert DTR and
wait for modem ready (DSR). DSR is the
indication that the call has been established. This sequence allows the DMV11
to automatically answer all incoming calls
to the LSI-11 computer station. If a valid
DDCMP message is not received within
30 seconds after a connection is established, DTR 1s dropped (hang up the
telephone).

POWER-ON

OFF

Allows the power-on boot feature at the
remote/tributary station. The node which
is to receive the boot requests the host
station to start the primary MOP boot
procedure. The BOOT request is sent out
when the first poll message after the
remote station’s power-up sequence 1S

b /—-\\

AUTO ANSWER

BOOT ENABLE

complete.

REMOTE LOAD

OFF

DETECT ENABLE

Allows the remote load detect boot feature at the remote/tributary station. The
host node starts the booting sequence by
starting the primary MOP boot
procedures.

6,7,8

MODE OF

OPERATION

ON or OFF

(as applicable)

These three switches define the DMV11
module’s mode of operation, at device
boot (initialization) time, if switch 1 is set
to the “OFF”’ position. Refer to Table 4-5
for a listing of the different switch positions and the operating modes they
define.
-

Table 2-6 DMV11 E101 (M8064)/ E107 (M8053) Switch Selectable Features (Cont)

Switch

HIGH SPEED

‘Number

Name

Switch Position

Switch

when Function
is Enabled

OFF

DMYV11 Function/Description
when Switch is Enabled

Selects the baud-rate that the DMVI1
operates at:

HIGH SPEED = “OFF” = 19.2K b/s

and greater

LOW SPEED = “ON” = <19.2K b/s
NOTE
The integral modem requires switch 9 to be set to

the enabled (“OFF”) position.
10

INTERFACE

“ON” _

ON or OFF

SELECT

“OFF” =

CCITT V.35 modem inter-

face selected.

EIA RS-232-C or RS-423-A

modem interfaces selected.
NOTE
Switch 10 is not used with the M8064 (integral
modem) DMV11-AC option module.

2-14

Table 2-7

Cabinet Kits

Cabinet
Kit

Description

CK-DMVI11-AA

Cabinet kit for EIA RS-232-C with 53.34 cm (21 inch) cable for PDP-11/23S 7020863-00 panel, H325 test connector, and BCO8S-1K cable.

CK-DMV11-AB

Cabinet kit for EIA RS-232-C with 30.48 cm (12 inch) cable for Micro-11 7020863-00 panel, H325 test connector, and BC08S-12 cable.

CK-DMV11-AC

Cabinet kit for EIA RS-232-C with 76.20 cm (30 inch) cable for PDP-11/23+
70-20863-00 panel, H325 test connector, and BC0O8S-2F cable.

CK-DMVI11-BA

Cabinet kit for V.35 with 53.34 cm (21 inch) cable for PDP-11/23S 70-20864-00
panel, H3250 test connector, and BC08S-1K and BC17E cables.

CK-DMVI11-BB

Cabinet kit for V.35 with 30.48 cm (12 inch) cable for Micro-11 70-20864-00
panel, H3250 test connector, and BC08S-12 and BC17E cables.

CK-DMV11-BC

Cabinet kit for V.35 with 76.20 cm (30 inch) cable for PDP-11/23+ 70-20864-00

panel, H3250 test connector, and BCO8S-2F and BC17E cables.
CK-DMV11-CA

Cabinet kit for integral modem with 53.34 cm (21 inch) cable for PDP-11/23S
70-20862-00 panel, H8568 and H8570 test connectors, and 70-18250-1K cable.

CK-DMV11-CB

Cabinet kit for integral modem with 30.48 cm (12 inch) cable for Micro-11 7020862-00 panel, H8568 and H8570 test connectors, and 70-18250-12 cable.

CK-DMVI11-CC

Cabinet kit for integral modem with 76.20 cm (30 inch) cable for PDP-11/23+
70-20862-00 panel, H8568 and H8570 test connectors and 70-18250-2F cable.

CK-DMVI1I-FA

Cabinet kit for RS-423-A /449 with 53.34 cm (21 inch) cable for PDP-11 /23S
70-20864-00 panel, H3251 test connector and BCO8S-1K cable.

CK-DMVI1I1-FB

Cabinet kit for RS-423-A/449 with 30.48 cm (12 inch) cable for Micro-11 7020864-00 panel, H3251 test connector, and BC08S-12 cable.

CK-DMVI1I-FC

Cabinet kit for RS-423-A /449 with 76.20 c¢m (30 inch) cable for PDP-11/23+
70-20864-00 panel, H3251 test connector, and BCO8S-2F cable.

2-15

CONNECT CABLE BCO8S FOR V.35 INTERFACE

H3254

TEST CONNECTOR

H3255

TEST CONNECTOR

SIDE 1

CONNECT CABLE BCOSS

FOR RS-232-C OR RS-423-A

M8053

INTERFACE.

TK-11008

Figure 2-6

Test Connector Insertion for the M8053

2-16

CONNECT 70-18250

H3254

TEST CONNECTOR

l 34IS

FOR INTEGRAL MODEM

‘

M8064

MK-2699

Figure 2-7

Test Connector Insertion for the M8064

2-17

ma&O
myYo

REC CLK +
TXCLK +
NULL CLK -

RECCLK -

TXCLK TX DATA A
N

R DATA +
TX DATA +
R DATA

RTS

JEREREEREE

NULL CLK +

CTS
REC RDY

HRERE

TER RDY

DATA MODE

TXINT

VIEW A
H3254 MODULE TEST CONNECTOR (J1 ON M8053/M8064)

TX CLK DIFF + —a—ro

RX CLK DIFF 4 —a—

AUX CLK = —»—

TX DATA DIFF +

il
J

RX DATA DIFF 4 —a——

TX DATA DIFF = ——

VIEWB

CDET

CTS

H3250

DTR

DSR

J-

[

RTS

RX DATA DIFF =

JoX

RX CLK DIFF
-

msf

TX CLK DIFF -

/-v‘%»\\“

AUX CLK + —»—

(D+:D'DXN+E<-<C}

MK-2645

REC INT

H3254

TXINT

SIDE1

|
MK-2123

Figure 2-8

DMV11 Test Connectors (Sheet 1 of 4)

2-18

REC COMMON

—————

TERINSER

—p——

INCOMING CALL

—a=——=

TER RDY +

DATA MODE +

-——e—

SEND DATA +

REC DATA +

—e—

SEND DATA =

——1—0—

REC DATA —=

—<——8—

NULL CLK +

—-——-T

SEND TIMING +

—-4———-3—

SEND TIMING—
REC TIMING —
RTS +

REC TIMING + —4———E0E—
NULLCLK= —>—1—&

HEREER L LU

F PP rep)-

SEND COMMON

—e

+
REC RDY

«———

SEL SIGNAL RATE

SIGNAL RATE IND

;

- * SEC RTS

_.—-4—3—

* SEC CTS

—4——-T

LOCAL LOOP

_'_'"_E_

TEST MODE

—‘—-—-COC—

SEL STAND BY

—"—T

STAND BY IND

—“——'—A':A—
—’——'-—%

CTS —

—<4— e

—4—

TH2

TH1

RTS -

o—

>
NN
"""—_°p"'

REC RDY =

SIDE 1

% SEC SEND DATA
¥ SEC REC DATA

_>-—-—-Ho+-+—
ey _:l
>

—mee—t—_—

SIGNAL QUALITY

m-_

cTS +

NEW SIGNAL

—‘_-_\}F
—

VIEW C

H3255 MODULE TEST CONNECTOR (J2 ON M8053)

—

DATA MODE =

=—®— - —

—
TER RDY

—4—@

3 NOT REQUIRED FOR DMV11
MK-2644

Figure 2-8

DMV11 Test Connectors (Sheet 2 of 4)

2-19

——

(1)

SHIELD GROUND

SIGNAL RATE INDICATION ——4—-—3
¢

SEND DATA +

SEND TIMING +

REQ DATA +

REQ TO SEND +

+
CLEAR TO SEND

100

LOCAL LOOP

° READY +
TERMINAL

12
%

RECEIVER READY +

104

INCOMING CALL

SIGNAL RATE SEL

107

TERMINAL TIMING +

118

TEST MODE

REQ TIMING +

DATA MODE +

REMOTE LOOP

%
-

1N
% 20
88

SIGNAL GROUND

200

RECEIVE COMMON

201

SEND DATA

22
3

REQ DATA

REQ TO SEND-

2¢5

>l
—

;’

CLEAR TO SEND
-

TERMINAL IN SERVICE

2;9

—

REQ TIMING
-

"m\

ND TIMING

DATA MODE

TERMINAL READY-

30
—»——0—31

RECEIVER READY
-

—<—+32

SELECT STANDBY

——>-—-—¢33

SIGNAL QUALITY

———

NEW SIGNAL

343

TERMINAL TIMING
-

STANDBY INDICATION

;

SEND COMMON

H3251

VIEW D

H3251 CABLE TEST CONNNECTOR

/,’_—afiv-\\

MK-2746

Figure 2-8

DMYV11 Test Connectors (Sheet 3 of 4)

2-20

H325

SCT —

SEC XMI T et

CUT TO TEST

SEC RCV

XMIT DATA

RCV DATA
"

NEW

o
4

SYNC

- SIDE 10——+—-o

-—*fi

.oooooooooooo R

O&.ooooooto..ojO
L

NEW stc—-——H—'

H326

DATA SET RDY',"'"‘—-G—CUT TO TEST*
NEW SYNC

DTR

VIEWE

H326 CABLE TEST CONNECTOR
MK-2124

Figure 2-8

DMV11 Test Connectors (Sheet 4 of 4)

2-21

VIEW A

NX<<4DZrrnOwW

HERREENEEE

BEEREERRREE

<sCWVITVZXIMO>»

NX<HITZrrcnOm®

40-PIN SOCKET

BCO8S (RS-232-C/V.35/RS-423-A, RS-449 INTERFACE) PANEL CABLE
TK-11009

—
]—

000000000000

o A

o] 000N0O0O000000

%)
5]

VIEW B

l 5
|

25 PIN

CONN.

'BC22F-10 (RS-232-C INTERFACE) MODEM CABLE
TK-11010

0000000 000000000000
00 0000000000000000

VIEW C

37 PIN

CONN.

BC55D-33 (RS-423-A/449 INTERFACE)MODEM CABLE
TK-11011

Figure 2-9

DMVI11 Cable Drawings (Sheet 1 of 3)

2-22

VIEW D

—

ool

—as

_ :iill

)

§8

55
o}

37 PIN
BC17E (V.35 INTERFACE) MODEM CABLE

CONN.
TK-11012

(170

VIEW E

PR4

BC56D TWINAX CABLE (WITH FEMALE CONNECTOR)
NOTE:

BC56A CABLE IS SIMILAR TO BC56D AND BC56B CABLE IS
SIMILAR TO BC56E, EXCEPT BOTH USE TRIAX CONDUCTORS
RATHER THAN TWINAX. ALL USE H8568 AS AN ADAPTOR.

40—
.

BC56E TWINAX CABLE (WITH MALE CONNECTOR)
TK-11013

VIEW F

—

| .

BC55T TWINAX CABLE

NOTE:

BC55S CABLE IS SIMILAR TO BC55T CARBLE, EXCEPT
USES TRIAX CONDUCTOR RATHER THAN TWINAX. BOTH ALSO
USE H8568 AS AN ADAPTOR.
TK-11014

Figure 2-9

DMVI11 Cable Drawings (Sheet 2 of 3)

2-23

VIEW G
70-20862

' 70-18250

__oTX
J1

|
J3

ORX.H

70-20862

CONNECTOR PANEL
(FRONT VIEW)
70-18250 (INTEGRAL MODEM)PANEL CABLE

NOTE:

TYPE OF DUPLEX OPERATION MUST ALWAYS BE ESTABLISHED
BY VIEWING CONNECTOR MATING FROM SIDE 2 (REAR
SIDE OF 70-20862 ASSY, OR SAME SIDE AS SWITCH S1).
HALF (BLUE) SIDE OF CONNECTOR FACING VIEWER PROVIDES HALF;
FULL (RED) SIDE.OF CONNECTOR FACING VIEWER PROVIDES FULL.
'

TK-11015

VIEW H

‘

H8568
TEST CONNECTOR

H8570
TERMINATOR
TK-11016

Figure 2-9

DMV11 Cable Drawings (Sheet 3 of 3)

2-24

RS-232-C INTERFACE

BCO8S

CABLE

J2 TEST

—

3 S1

MODE

1-5
— S2
6-10
L] g3
11-156
—1

_—16-20

M8053

BC22E OR BC22F CABLE

DMV 1 -RS-232

H325 TEST

CONNECTOR

H3255

70-20863
PANEL

V.35 INTERFACE
BC17E CABLE
BCO8S

CABLE

= DMV11-RS-423"
®)

(o)

DDS
MODEM

=l
J2

M8053

J1 TEST

H3250 TEST

@)
O

CONNECTOR

e T

CONNECTOR
H3254

70-20864
PANEL

RS-423-A/449 INTERFACE
BC55D CABLE

BCO8S

CABLE

~DMV11-RS-423"
@)
o A

MODEM

B
O \/

H3251 TEST

CONNECTOR

J2 TEST

\\ CONNECTOR
|

H3255

70-20864
PANEL
TK-11017

Figure 2-10 DMV11 Remote System Cabling Diagram
2-25

FULL-DUPLEX

INSTALL 75
TERMINATOR

’”W
@Js % BC55T /

IN J2

70-20862

PANEL

"@TX :

)
J1

CONNECTOR (H8570)

)

70-18250

M8064

I/.
3

.
)]

N
h’

M8064

‘

BC55T

70-20862

INSTALL 759

PANEL

TERMINATOR

CONNECTOR
(H8570) IN J2

70-18250

HALF-DUPLEX

INSTALL 759
TERMINATOR

CONNECTOR (H8570)
70-18250

IN J3

TX N
J1@@ RX

J2” )

M8064

BC556T

S, B I

70-20862
PANEL

M8064

‘'
J1

70-20862

INSTALL 752

PANEL

TERMINATOR

I
CONNECTOR (H8570)

70-18250

IN J4
NOTES:

Figure 2-11 DMVI11 to DMV11 Integral (Local) Modem Cabling Diagram (Point-to-POint)

2-26

HDX NETWORK

TERMINATOR

(H8570)

CONTROL

J3
‘

STATION

70-18250

70-20862
PANEL

BCB5T |
|
|
|

| o L

M8064

TRIBUTARY

‘
‘‘
TXI 1| 7048250
|

70-20862
PANEL

BC55T |

|F
|

|
|

M8064

: O

TRIBUTARY

‘
‘
‘
‘ 7 70-18250
TX]

70-20862

BC55T

PANEL

r——=—=

I
|

O
J4

M8064

l O

TRIBUTARY

o“hx o
xT

70-18250

70-20862

TERMINATOR

PANEL

(H8570)
TK-11019

Figure 2-12

Half-Duplex Multipoint Network (Control Station End Node)

2-27

FDX NETWORK

TERMINATORS

70-20862

(H857/O)
e fi

PANEL

M8064
J1

STATION

k'“l
TX]

70-18250

|
|

|
i

BC55T

70-20862

PA NEL

M8064
o

TRIBUTARY

©) J3 @ J1

VO‘

70-18250

TX]

TRIBUTARY

70-20862
PANEL j

|
70-18250

2ORgC
o
7 O
»

CONTROL

'BC55T

|
|

70-20862

PANEL

M8064

Jl4

TRIBUTARY

|
|

0 OO
) O

70-18250

TERMINATORS
(H8570)
NOTES:

SOLID LINE REPRESENTS CONTROL STATION TRANSMIT TO
TRIBUTARY RECEIVE.
DASH LINE REPRESENTS CONTROL STATION RECEIVE FROM
TRIBUTARY TRANSMIT.

BOTH ENDS OF THE TRANSMIT LINE FROM THE TRIBUTARIES NEED TERMINATION
IN ADDITION TO THE ONE TRANSMIT LINE FROM THE CONTROL STATION.
TK-11021

Figure 2-13 Full-Duplex Multipoint Network (Control Station End Nodé)
2-28

FDX NETWORK

TERMINATORS
(H8570)

M8064

70-20862
PANEL

TRIBUTARY

70-18250
o

BC55T

]

CONTROL

70-20862
PANEL

STATION

70-18250

TRIBUTARY

70-20862
PANEL

9
o

&©

_
70-18250

_
L
|

~—BC55T

PANEL

V8064

70-20862 ~
Lo T

|92

70-18250

/
RX

TRIBUTARY

]

TERMINATORS
(H8570)

NOTES:
SOLID LINE REPRESENTS CONTROL STATION TRANSMIT TO
TRIBUTARY RECEIVE.

DASH LINE REPRESENTS CONTROL STATION RECEIVE FROM TRIBUTARY
TRANSMIT.

SINCE THE CONTROL STATION IS NOT AN END MODE THERE IS A NEED TO

TERMINATE TWO SETS OF TRANSMIT LINES FROM THE CONTROL STATION.
ADDITIONALLY BOTH ENDS OF THE TRANSMIT LINE

FROM THE TRIBUTARIES.
-~

TK-11020

Figure 2-14 Full—Duplex Multipoint Network (Control Station Inner Node)
2-29

2-30

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BEELLI-AL

2.6 DMV11 SYSTEM TESTING
The final step in the installation of a DMV 11 subsystem is to exercise the DMV 11 as: 1) a unit on the LSI-

11 bus; and 2) a link in a communications network.

2.6.1

Functional Diagnostic Testing
Ensure that the specific cable turnaround test connector for the selected DMV 11 option is still installed at
the end of the cable. Load and execute the DMV 11 functional diagnostics with the external mode selected.
Upon obtaining a minimum of five error-free end passes, proceed to Section 2.6.2.

2.6.2

DEC/X11 System Exerciser

The DEC/X11 system exerciser for the DMV11 can be run in two different operating modes, internal and

external. The internal mode selects faster LSI-11 bus activity. The external mode requires that the specific
modem test connector be installed at the end of the cable. This is the preferred mode of operation. There
are two DEC/X11 modules for the DMV11; DMD* and DME*.
2.6.3 Final Cable Connections
The final step in the installation process is to return the DMV11 to its normal cable connections, either to
the appropriate modem or to the distribution panel. The DMV11 system cabling diagrams in Figures 2-10
through 2-14 have been included to help show overall cabling for the various DMV11-XX options.
References to specified locations of the various test connectors during diagnostic testing are also included.
After the cables are connected to the appropriate modem or distribution panel, it is suggested that the data
communications link test program (DCLT) be exercised.
2.6.4 DMYVI11 Link Testing
The DMV11 can be exercised over a communications link by the data communications link test (DCLT).
It is suggested that DCLT be configured to run first on a cable test connector and then on a modem with

the modem analog loopback test feature selected (if the modem includes this feature). Next, the overall

communications link should be exercised with the remote computer system that contains a DMV11.

2-31

CHAPTER 3
COMMAND AND RESPONSE STRUCTURES

3.1
INTRODUCTION
This chapter defines DMV11 command and response formats in all necessary detail, and describes all
programming sequences relevant to DMV11 operation in the network environment. The CSR command
structure and format of input commands and output responses, as well as data port descriptions, are
described in detail. Discussions include special programming techniques, user access to maintenance
mode, and user interpretation of status/error reporting.
3.2 COMMAND STRUCTURE
The DMV1I1 command set is structured into two categories; input commands and output responses.
Brief overviews of input commands and output responses, including command codes and the handshaking requirements, are provided in this section.
Transfer of control and status information between the main CPU resident user program and the
DMV11 is accomplished through four 16-bit control and status registers (CSRs). Input commands are
issued to the DMV11 by the user program, and output responses are issued to the user program by the
DMV11.

NOTE
Normally only four CSRs are used, butin the 22- blt
address mode, eight CSRs are available.
3.2.1
Control and Status Registers
Four 16-bit CSRs are used to transfer control and status information. These registers are both byte and
word addressable. The eight bytes are assigned addressesin the floating address space in the I1/O page
as follows:
16XXX0, 16XXX1, 16XXX2, 16XXX3, 16XXX4, 16XXX5, 16XXX6, and 16XXX7.

For discussion, these byte addresses are designated byte select 0 through 7 (BSELO through BSEL7).

BSEL10 and BSELI11 are only used in 22-bit address mode. BSEL12 through BSEL17 are not used by
the user/DMV11-command structure and are not referred to in this document.

The four word addresses are the even numbered locations and are designated select 0, 2, 4, and 6
(SELO, SEL2, SEL4, and SEL6). The CSR addresses are assigned to the floating address space. The
floating address ranking for the DMV11 is 24 (See Appendix B). The relationship between the symbolic byte and word addresses for DMV11 CSRs, and the actual CSR layout, is shown in Figure 3-1.
Figure 3-2 illustrates the fields in CSR bytes BSELO, BSEL2, and BSEL3 that comprise the fixed
format portion of both user-program commands and DMV
11 responses. This fixed format portion serves to identify the command/response type, address of the tributary that the command /response applies
to, and coordinate ownership of the CSRs between the DMV11 and the user program. Detailed bit
descriptions of SELO and BSEL2 are provided in Tables 3-1 and 3-2 respectively.

The four bytes comprising SEL4 and SEL6 contain the fields pertinent to each ‘user-program command
and DMV11 response. Detailed descriptions of the SEL4 and SELS6 fields are presentedin Sections 3.3
through 3.4.

3-1

8 7

’//Mm\\

BSEL1

BSELO

SELO

BSEL3

BSEL2

SEL2

BSELS

BSEL4

SEL4

BSEL7

BSEL6

SEL6

Eseio

SEL10¥

| Bsem

*¥SEL10 IS ONLY USED IN 22 BIT ADDRESS MODE
MK-2660

DMV11 CSRs Byte and Word

Figure 3-1

Symbolic Addresses

L
.
.
'
'

'
.
|

|
.
|

BSELS
|
BSEL

{

0 I RQl
‘ RDO
|

|
.
'

]

|
o
RDI

COMMAND/RESPONSE
FIELDS
COMMAND/RESPONSE

.
.
e

FI.ELDS !
7

]

IEl | BSELO
. | COMMAND
SELS
"CODETYPE | BSEL2

IEO

| TRllBUTAFiY AD[?RESS |

BSEL3
’

)

BSEL4
SEL4
BSEL6

S
'
.
L

,
|
2

SELG

MK-1636

*22-BIT
MODE

Figure 3-2

Fixed and Variable Formats for Commands and Responses

Table 3-1

Bits

Name

SELO Bit Functions

Description

BSELO

~ Interrupt

When set, this bit enables the DMV11, upon asserting RDI (bit 4

Enable In (IEI) | of BSEL2), to generate an interrupt to vector address XXO.

1-3

Reserved

Interrupt
Enable Out

When set, this bit enables the DMV11, upon asserting RDO (bit
7 of BSEL2), to generate an interrupt to vector address XX4.

(IEO)

5-6

Reserved

3-2

Table 3-1
Bits

SELO Bit Functions (Cont)

Name

Description

Request In
(RQI)

This bit is set by the user program to request access to the data
port. It is cleared by the user program when the data port is not
required for further issuing of commands. The user program may

leave RQI set if successive requests for the data port are pending.

BSELI

Maintenance
Request

When set, along with master clear (bit 14 of SEL4), this bit
causes the DMV11 to enter the maintenance register emulation
section of the microcode.

- NOTE
Detailed discussion of maintenance register emulation is presented in Section 4.8.

9-10

Reserved

Diagnostic

When set, this bit allows diagnostic programs to change the mode

Mode

of operation of the DMV11 using the mode definition command to
override the mode switches. Additionally, when set during a mode
definition command, this bit causes the DMV11 not to set data

terminal ready (DTR).
12

Reserved

Invoke P/MOP | Invoke primary MOP mode. When set to one, this bit causes the
Boot
DMV11 at this multipoint station to request that the control station initiate the primary MOP (maintenance operation protocol)
boot procedure. In point-to-point networks, a DMV11 having this
bit set requests the other station to initiate the primary MOP
boot procedure.

NOTE
" The master clear bit (bit 14) must also be asserted
to use mvoke P/MOP.

Master Clear

When set, this bit 1n1t1allzes the DMV11. The clock is enabled
and the RUN flip-flopis set. Master clear1s self-clearing.

Run

This bit controls running of the microprocessor It 1s set by bus
initialization or master clear. When run 1s cleared the microprocessor halts.

3-3

Table 3-2

BSEL2 Bit Functions

Description

Bits

Name

0-2

Control/Response | These bits define the type of input command or output res'ponse as folCode

lows.

Description

Bits
210

Buffer address/character count
(RCV) command or buffer disposition (RCV complete) response

0 0

Control command or control re-

sponse

Mode definition command or

information response

Bufferdisposition (RCV unused)

response

Buffer address/character count
(XMIT) command or buffer disposition (XMIT complete) re-

sponse

Reserved

Buffer disposition (sent but not

acknowledged) response

Buffer disposition (not sent)
response

22-Bit Mode

This bit when set indicates to the DMV11 that the buffer address 1s in

Ready In
(RDI)

RDI is the DMV11 response to RQI, indicating to the user program
that it has control of the CSRs to issue a command. It is cleared by the
user program when the data port contains the input command. Clearing

the 22-bit format.

RDI returns control back to the DMVII.

5-6

Reserved

Ready Out
(RDO)

RDO is asserted by the DMV11 to indicate that the data ports (SEL4
and SEL6) contain an output response for the user program. The user

program must clear RDO after it has read this information. Clearing
RDO returns the CSRs to the DMV11.

3-4

3.2.2 Input Commands Overview
In general, input commands provide the means for the user program to assign, receive, or transmit buffers to the DMV11. Detailed field descriptions and formats of each input command are provided in
|
Section 3.3
There are four types of input commands that can be issued to the DMV11 for execution.
Microprocessor control/maintenance command;
Mode definition;

Control;

Buffer address/character count.
With the exception of the microprocessor control/maintenance command, input commands require an
identification code in the first three bits of BSEL2 (see Figure 3-2). These codes, which define each
command and variations of specific commands within the command set, are defined in Table 3-2 and
listed in Table 3-3.
'NOTE

CSR addresses are expressed in octal.

Table 3-3

Input Command Codes

Input Command Type

|
Mode definition

Control

Binary Code(BSEL2)

~ Bit

Bit

1 |

Buffer address/character count

(receive)

(transmit)

3.2.3 Output Responses Overview
Output responses provide a means for the DMV11 to report various normal and abnormal (error) conditions concerning the data transfer operation. Three basic responses are provided:
e
e
e

Buffer disposition;
Control;
Information.

The buffer disposition response is used to return both used and unused buffers to the user program.

The control response is used to report error conditions concerning the microcontroller/line unit hardware, data link, physical link, or remote station. It also passes protocol information to the user.
The information response provides information requested by a control command from the user program.

3-35

3.3

DMV11 INPUT COMMANDS

This section provides detailed descriptions of each input command. Command formats and data port
~ usages are illustrated and defined. User-program execution requirements, command variables, and action taken by the DMV11 in response to commands are discussed.
3.3.1

Microprocessor Control/Maintenance Command

This single byte command has two functions; to initialize and cause the DMV11 to start running, and to

cause entry into the microcode maintenance loop when the maintenance request bit is set. At start-up
time under normal operating conditions, this is the first command issued by the user program in order
to initialize the DMV11.

The format for the DMV11 initialization register (BSEL1) is shown in Figure 3-3. To set the master
clear bit and thereby cause entry into the DMV11 running mode, the user program moves a byte with
an octal value of 100 to BSEL1. As a result, all condition-sensitive logic in the DMV11 is reset for startup, and the start-up diagnostic is executed. When the diagnostic completes satisfactorily, the run bit in
BSELI is set to one. This indicates that the DMV11 is running and the microcode is executing.
Figure 3-4 presents a flow chart describing how to initialize the DMVI11. A timeout counter is set to
avoid the possibility of the user program being caught in an endless loop in case the internal diagnostic
does not complete successfully.

‘7

5
6
MST[

BSEL1IRUN cLRr

3
DIAG

MODE

1
-~

0
[MNT}
~
|rRea

MK-2513

Figure 3-3

Microprocessor Control/Maintenance
Command Format

Mode Definition Command

3.3.2

Functionally, the mode definition command is used to establish the hierarchy of a network and the
characteristics of the communications line serving that network. As shown in Figure 3-5, the mode definition command contains two fields; the command type code field in BSEL2, and the mode field in
BSEL6. The mode field contains a code defining the function to be performed by the command.
With the mode definition command, the user program can designate the DMV11 as a control station, a
tributary in a multipoint network, or as a node in a point-to-point network. In addition, the characteristics (half-duplex or full-duplex) of the physical communications line connecting the network can be
defined.

The actual mode field codes and the functions implemented by each code are listed in Table 3-4.
Under normal operating conditions, the mode definition command is issued by the user program at

start-up time (after the internal microdiagnostics have executed successfully and the run bit is set).
Network discipline requires that each DMV11 in a network issue a mode definition command that is
appropriate to the network. For example, in a half-duplex multipoint network comprised solely of
DMVlls:

The user program at the control station issues a mode definition command with the mode

The user program at each tributary station issues a mode definition command with the mode

field set at four.

field set to six.

3-6

SET MASTER
CLEAR BIT
IN BSEL1

(BSEL= 1004
)

SET
TIME OUT

COUNTER
TO

> 0.5 SEC

RUN

BIT SET?

(BSEL1 =2008 )

DIAGNOSTIC
ERROR, EXIT
TO ERROR

CONTINGENCY

EXIT

EXIT TO
COMPLETE
START UP

MK-1638

Figure 3-4

Initialization of the DMVI11

3-7

This network discipline also applies to DMV11s operating in point-to-point networks with other
DMVl1ls, DMPl1s, DMCl11s, and DMR11s.
.
When tributary addresses are software assigned, the mode definition command must be used at the
‘control and tributary stations to configure the network and assign line characteristics.

The functions performed by the mode definition command can also be implemented by the mode selection switches on the DMV11 module. The switches must be used to establish mode definition functions
when tributary addresses are switch assigned. The switch setting for performing the mode definition
functions corresponds to the BSEL6 codes listed in Table 3-4.

Once the type of station is set, it can only be changed by a master clear or a physical change in the
switches. If the type of station is switch assigned, a master clear has no affect. However, the switches

are overridden when the diagnostic mode bit (bit 3 of BSEL1) is set and a mode definition command is

issued.

6
T

.
1

BSEL3

4
1

3
1

o
1

,
i

0 I RQl

BSELS

IEO

2
i

RDI

IEl | BSELO

]

BSELZ

CMD TYPE CODE

RDO
]

5
1

TRIBUTARY ADDRESS
1

|gg
9

s
i

BSEL4

. SEL4

MODE FIELD | BSEL6

BSEL7
15

|
4

]
1

SEL6
0
MK-1639

Figure 3-5

Mode Definition Command Format

Table 3-4

Mode Field Codes and Functions

BSELG6 Bit

Line

Network

DMC11-Line

Positions

Characteristics

Configuration

Compatibility?

Half-duplex

Yes
Yes
No
No
N/A

0O
0
0O
0
1

O
1
O
1
O

Half-duplex

Point-to-point
Point-to-point
Point-to-point
Point-to-point
Control station

1
1

0
1

1
O

Full-duplex
Half-duplex

Control station

N/A

Tributary station

N/A

Full-duplex

Tributary station

N/A

0
1
1

Full-duplex
Half-duplex
Full-duplex

3.3.3

Control Command

This command is the primary means of controlling the operation of DMV11-implemented networks.
The format of the control command is illustrated in Figure 3-6.

At start-up time, the user program at the DMV11 control station must issue one control command (establish tributary) for each tributary address supported in the multipoint network. This must be done
after issuing the microprocessor control and mode definition commands. This causes the microcode to
create a tributary status slot (TSS) in the DMV11 data memory for each tributary in the network.
Similarly, the user program at each tributary must issue a control command (establish tributary) for
each tributary to be established at that station. This causes a TSS to be created at that station for each
tributary it establishes.

In point-to-point networks, a control command (establish tributary) must be issued at both stations. The
tributary address field in this case must be a one. This results in the creation of a single TSS structure
at each station.

The DMV 11 microcode at the control station and at all tributary stations uses these TSS structures to
coordinate protocol operation over the network between the control/tributary pair. User programs, at
the control station and at the established tributaries, access these structures to obtain operational information such as:

/.\

The number of messages transmitted and received;
The number of selection intervals and timeouts;
The number of reply timeouts; and
The number of various types of errors.

BSEL3

{

|Rd

TRIBUTARY ADDRESS
1

BSELDS
——

B |

[

}

DATA

BSEL7

156

]
14

[13

|
10

POLLING

COMMON

STATE

BUFFER

POOL

POLLING
STATE

READ)

|fss

|TSS

IEI
0
1

}

TSS ADDRESS

| BSELO
BSEL2

|spLo

2251_4

REQUEST KEY OR

p"/|READ

TSS
8

DISABLE

CMD TYPE CODE

DATA

WRI

RDI

LATCH

UNLATCH

IEO

{

- g

RDO
1

BSEL6

SEL6
0

ENABLE
COMMON
BUFFER
POOL
MK-1640

Figure 3-6

Control Command Format

3-9

At the start-up of tributary stations having multiple software assigned tributary addresses, the user program at each station issues as many control commands as there are established tributaries at that node.
However, in networks where tributary addresses are switch assigned, only one control command specifying the switch assigned address is required as part of the start-up sequence. Any other nonzero tributary address in a control command is overridden by the switches.
The control commandis also used by the user program at the control station to specify a unique set of
polling parameters for each tributaryin the network.
During normal operation, the control station microcode can determine the polling level of any tributary
in the network and adjust the polling frequency of that tributary as necessary (see Section 5.2).
The control command permits the user program to perform a number of control functions using the
same command format. In general, each function implemented by this command requires issuing of a
single appropriately formatted control command. SEL6 is used to define the various functions of the
control command (see Figure 3-6). Table 3-5 provides a detailed description of each bit or field.

Table 3-5

Bit | Name
0-4 | Request Key

SEL6 Control Command Functions

| Description
These five bits are encoded requests from the user program. When this field is
used, bits 5 through 7 must be cleared. Request keys are encoded as shown in
Table 3-6.

|Read TSS/GSS | A control command with this bit set, allows the user program to read two consecutive locations (two bytes) of a tributary status slot (TSS) or global status
slot (GSS) without modifying it.
The TSS to be read is specified in BSEL3 and the location within the TSS is
specified in bits 0-4 of BSEL6. Notice that bit 5 is also set to indicate a read
GSS. To read a GSS location, BSEL3 is zero.
When the DMV11 receives a control command to read a TSS or GSS location,

it passes the requested information to the user program through an information
response (see Section 3.4.3). However, the requested information is placed on
an internal queue before it is passed to the user program. As a result, the information requested may change before the user gets it. This is particularly true
for number of messages transmitted/received and selection intervals.

|Read and
- A control command with this bit set, allows the user program to read and clear
Clear TSS/GSS | specific locationsin a TSS or GSS.

The TSS to be read is specified in BSEL3 and the location within the TSS is
specified in bits 0-4 of BSEL6. Notice that a read and clear command bit 6 of
BSELS6 is also set. This gives a base octal value of 100 to which the specific
TSS address is added. To read and clear a GSS location, BSEL3 is zero.

Only the error counter sections of the TSS (7-17 octal) and GSS (15-17 octal)
can be accessed with a read and clear command.

3-10

Table 3-5

Bit | Name

SEL6 Control Command Functions (Cont)

Description
Accessing any other locations results in a procedural error.

Valid octal values for BSEL6 for the read and clear function are listed below:
Octal Value

TSS Location

107
110
111
112
113
114
115
116
117

Data messages transmitted
Data messages received
Selection intervals
Data errors outbound
Data errors inbound
Local buffer errors
Remote buffer errors
Selection timeouts
Local and remote reply timeouts

Octal Value

GSS Location

115
116
117

Remote station errors
Local station errors
Global header blockcheck and
maintenance data blockcheck
errors

These errors are covered in
detail Section 5.3.

When the DMV 11 receives a control command to read and clear a TSS or GSS
location, it passes the requested information to the user program through an information response, and then clears the location.

As in the case of the read TSS/GSS, the information is placed on an internal

queue and is subject to change before the user gets it. However, by reading and
clearing, the user can keep a cumulative total.

Write TSS

A control command with this bit set, enables the user program to write into specific locations in an associated TSS or GSS.

The TSS to be written into is specified in BSEL3 and the specific location within the TSS or GSS is specified in bits 0-4 of BSEL6. To write to a GSS loca-

tion, BSEL3 is zero.

Notice that bit 7 of BSELSG is also set to indicate a write TSS. This gives a base

octal value of 200 to which the specific TSS address is added.

3-11

" Table 3-5

Description

The data to be written is contained in BSEL4 and BSELS5. There are eight TSS

and five GSS parameters that can be written:

TSS PARAMETER

BSEL6

Transmit delay timer (XDT)

Initial polling urgency (Q) and
polling rate (R) for active
state

230

231

Initial polling urgency (Q) and
polling rate (R) for inactive
state

232

Initial polling urgency (Q) and
polling rate (R) for unresponsive
state

233

No data message count (non-inact)
and unresponsive timeout count
(TO-UNRESP)

6.
7.

234

Dead timeout count (TO-DEAD)
and maximum message count (MMC)

235

Selection interval timing
|

236

counter

Babbling tributary counter

237

See Table 4-2 for details
GSS PARAMETER
l.
2.

4.
5.

BSELG6

Number of sync-characters to
precede nonabutting messages

233

Preset value for streaming
tributary time counter

234

Polling algorithm update
interval (DELTA T)

235

Polling rate for dead tributaries (DEAD T)

236

Fixed polling delay (poll
delay)

237

See Table 4-3 for details
NOTE

Some parameters are 8-bits in length. Thus, in those
cases two parameters are indicated. All user accesses are on two byte boundaries.

3-12

Name

Bit

SEL6 Control Command Functions (Cont)

Table 3-5

Name

Description

Enable

A control command with this bit set allows a specified tributary (BSEL3) to use
the common receive buffer pool. Usage of the common pool is based on a common pool quota. This quota is determined for the specified tributary by adding
the octal value in BSEL4 to the current quota. If this results in a value equal to
or greater than 377 octal, a procedural error results and the quota is reset to
376. However, a tributary may be set up for unlimited use of the common pool
by setting BSEL4 to 377. Each time a tributary uses a common pool buffer, the
quota is decremented by one. When the quota reaches zero, the tributary is prevented from using the common pool. See Section 3.3.4 for more details on common buffer pool.

Common

SEL6 Control Command Functions (Cont)

Pool

The common pool is checked first. If no buffers are available or the quota is
zero, or the buffer is too small, the private receive buffers are checked.

Disable
Common Pool

A control command with this bit set, disables the use of the common receive
buffer pool for the tributary specified in BSEL3.

The quota previously established for this tributary is cleared to zero.

Reserved

Unlatch Polling State

A control command with this bit set, causes the polling state level of the tributary addressed by BSEL3 to go to the active polling state. Control of the polling

activity for the specified tributary is then returned to the polling algorithm.

Latch Polling State

A control command with this bit set, establishes the polling state of the tributa-

ry addressed by BSEL3. The polling state is determined by bits 0 and 1 of
BSEL4. These bits are encoded as follow:
Bits
00
01
10
11

1& 0

Polling State
Active
Inactive
Unresponsible
Dead

3-13

Table 3-6

Request Key Field Definitions (Control Command)

Octal
Code

Name

Description

No Request

This code allows the issuing of a null control command for the purpose
of returning control of the CSRs to the DMVI11. The no request code
is used when RDIis set but thereis no command to 1ssuc (see Section
4.2.3). Thisis effectively an NOP command.
NOTE
The
enable/disable
common
pool
and/or
latch /unlatch polling state bits in BSEL7 can be
used in conjunction with this request key.

This control function initiates the creation of the tributary status slot

(TSS) data structure. This must be accomplished before any command is issued that uses a tributary address.

The user program at the control station must issue one establish tributary control command for each tributary supported in the network.
The tributary address is designated in BSEL3.

NOTE

As a result of establishing one or more tributary addresses, the
DMV11 creates a global status slot (GSS). This GSS is part of the
overall status structure at each station.
NOTE
This control command function can also be used
during normal operation of a multipoint network to
reestablish previously deleted tributaries. In such
cases, the tributary address must be reestablished at
both the control station and the pertinent tributary
station.
NOTE

The enable/disable common pool and/or the
latch/unlatch polling state bits in BSEL7 can be
combined with this control function in a single control command.

3-14

) ——
|

The DMV11 has 12 available TSS blocks. Each block has 64 — 8-bit
locations for storing status and other information necessary for maintaining communications over the data link.

In a point-to-point network, this control command,
with a tributary address of one in BSEL3, should be
issued at each station to establish the required TSS.

Establish

Tributary

Table 3-6

- Octal
Code
02

Request Key Field Definitions (Control Command) (Cont)

Name

Description

Delete

This control function removes a specified tributary from operational

Tributary

status by eliminating its associated TSS. Prior to issuing this command, the user program must first halt the tributary being deleted.
[See request key 05 (request halt state)]. The TSS can only be rees-

tablished by using an establish tributary function. Only 12 addresses
may be established at any one time.

Request Start-up
State

This control function initializes the designated TSS and initiates the
DDCMP start-up sequence for that tributary. BSEL3 specifies the tributary address. Request start-up state must only be issued to tributaries that are in the halt state.

When the start-up sequence is completed, the DMV11 notifies the
user program by issuing a comtrol response. When this response (run
state) is received by the user programs at the tributary and control
station, message traffic can begin between these two stations (see

,/;

Table 3-7).

NOTE
common pool and/or the
latch/unlatch polling state bits in BSEL7 can be
combined with this control function in a single control command.

The

Request Maint

State

enable/disable

This control function places the tributary designated by BSEL3 into
the DDCMP maintenance state.

A tributary placed in the maintenance state can only transmit and receive maintenance messages. Both the control station and tributary
must be in the maintenance state in order for maintenance message
traffic to occur.

The maintenance state must only be issued to tributaries that are in
the halt state.

- NOTE
common pool and/or the
latch/unlatch polling state bits in BSEL7 can be
The

enable/disable

combined with this control function in a single control command.

3-15

Table 3-6

Octal

Request Key Field Definitions (Control Command) (Cont)

Code

Name

Description

Request Halt

This control function places the tributary designated by BSEL3 into
the DDCMP halt state. All outstanding buffers are returned.

State

When a tributary is halted at the control station, the tributary is no
longer polled. When a tributary is halted by its own user program, it
no longer responds to polling.

The TSS for the halted tributary remains unchanged at both the control and tributary stations. The halted tributary can be restarted by
issuing a request start-up state control command.
NOTE

The halt state may also be used on a global basis to
return all common pool buffers. This is accomplished by using a tributary address of zero in
BSEL3 when issuing the request halt state.

Tributaries must not be using the common pool when
this function is issued. If the common pool is in use,
a procedural error of 136 is generated (see Table 37).

Write Modem

This control function permits the user program to write the contents of

Read Modem

This control function causes the DMVI11 to read the modem register

Control

BSEL4 into the DMV11 modem register. (See Appendix C).

and pass this information to the user program through SEL4 by way

of an information response. (See Appendix C.)
NOTE
Request key codes 6-17 and 22-37 are reserved.

3.3.4

Buffer Address/Character Count (BA/CC) Command

This command provides the user programs at both the control station and tributaries with the means to
assign, transmit, and receive buffers.

The format for this command is shown in Figure 3-7. Note that the command has two forms to facilitate
separate management of transmit and receive buffers. These two forms are distinguished by the type
code in BSEL2. A type code of zero is used to allocate receive buffers and a type code of four is used to
allocate transmit buffers.

and bits 14
The tributary address is specified by BSEL3 and the buffer address is contained in SEL4 notation.
A
and 15 of SEL6. The remaining 14 bits of SEL6 contain the character count in positive
character count of zero is illegal.

3-16

In addition to allocating receive and transmit buffers, the buffer address/character count command is
used to allocate common receive buffers by specifying a tributary address of zero in BSEL3. These
buffers can only be used by tributaries authorized to do so by the enable common pool bit of a control
command.
When the user program has a message to transmit, it informs the DMV11 of the size and address of the
message buffer. This is done by the buffer address/character count command on a one buffer per command basis. A tributary address of zero when assigning transmit buffers results in a procedural error.

When the user program is receiving messages, it assigns receive buffers on a one buffer per command

basis using the buffer address/character count command. These buffers may be in the common pool of
buffers or be private buffers. Each BA/CC command used to assign a buffer to be the common pool
must contain a zero in BSEL3. Although this command assigns buffers to a common pool, actual allocation is performed through the control command by enabling access to the common pool on a per tributary basis.

;

)

| TRIBlUTAR\l( A DDF}ESS |

BSELS

BUFFER ADDRESS

)

| R

RDI

IEl

cope*

CHARACTER COUNT
| LOW lBYTE ‘

|BSELO

|BSEL2
SELD

CMD TYPE

LOW BYTE

BUFFER ADDRESS

HLIGH S!X BITSI

RDO

" CHARACTER COUNT
:

. HIGH BYTE,

asgL7| B/A | B/A

BSEL3I
'
’ “\\

BSEL4

)

SEL4

18 BIT ADDRESS MODE

BSEL6

SEL6

0
|
MK-1641

;

BSEL3

L TRI?UTAR\L( ADDLRESS |

BSELS

BSEL7|

BUFFER ADDRESS

HIGH BYTE,

UNUSED

BSEL11

UNULSED
15

R Ql

CHARACTER COUNT

»|

22BIT|

BUFFER ADDRESS

|BSEL2

coDE*

SELo

BSEL4
SEL4

BUS ADDRESS BITS 16-21

‘

SELE

[]

. LOW BYTE |

LOW BYTE

]

CHARACTER COUNT
5

|BSELO

IEl

CMD TYPE

RDI M?DE

IEO

UNUSED

HIGH SIX BITS

2
L

BSELG

BSEL10

SEL10
o)

22 BIT ADDRESS MODE

* TYPE CODES
BUFFER ADDRESS/CHARACTER COUNT COMMAND - RECEIVE = 000
BUFFER ADDRESS/CHARACTER COUNT COMMAND - TRANSMIT = 100

'//"'“\

MK-2512

Figure 3-7

Buffer Address/Character Count Command Format

3-17

In multipoint networks, user programs at both the control and tributary stations can handle allocation

of receive buffers in two ways:

The first method involves the allocation of receive buffers from a common pool of buffers.
With the common buffer pool enabled, receive buffers are assigned to the pool through the
buffer address/character count command on the basis of one buffer for each command issued. Each buffer address/character count command used to assign a buffer to the common
pool must contain a zero in BSEL3. Although this command assigns buffers to a common
pool, actual allocation to a tributary is done through the control command by enabling access
to the pool and assigning quotas (see Table 3-5).

In the second method, the user program can directly allocate private receive buffers based on
anticipated message traffic using one buffer address/character count command for each private buffer allocated. In this context, a private buffer is defined as a receive buffer assigned
to a specific tributary for its exclusive use, and in all cases the address of that tributary must

be in BSEL3 of the assigning command.

Private buffers and buffers from a common pool can be used jointly at control and tributary stations in
a multipoint network. Under these circumstances,
the advantages provided by both methods are available to the user program.

Private buffers can be set for unanticipated messages and/or abnormally large messages.

The preceding information involved standard 18-bit addressing. However, the DMV11 may also operate in 22-bit addressing mode. The DMV11 allows the software to set the 22-bit address mode of operation. The bit indicating 22-bit address mode is set by the user program as part of a command when
issuing transmit or receive buffers to the DMVI11. The state of this bit is retained to indicate to the
DMVI11 the number of bits in the buffer address.

3.4 DMV11 OUTPUT RESPONSES
The DMVI11 microcode has a set of three responses it can use to either reply to user-program commands or to inform the user program of error conditions. These responses are:

e
e

Buffer disposition response;
Control response;

Information response.

As with 'input commands, each output response is identified by a typecode in bits zero, one, and two of
BSEL?2.

NOTE
In multipoint networks, each response issued contains (in BSEL3) the address of the tributary that
relates to the response. However, in point-to-point
networks, equivalent responses always contain a one
in BSEL3.

3-18

3.4.1
Buffer Disposition Response
This response is used to return both used and unused buffers to the user program. Figure 3-8 shows the
format of this response and identifies the five methods of message disposition in BSEL2. BSEL?2 bits
zero, one, and two are encoded as follows:
Bit2

Bitl

Bit0

Buffer Disposition

Receive buffer complete

Receive buffer unused

Transmit buffer complete

Transmit buffer sent but not acknowledged

Transmit buffer not sent

Receive Buffer Complete — When a message is received successfully and stored in the assigned main
memory buffer, the DMV11 microcode notifies the user program by issuing a buffer disposition response with a type code of 000. Data in the receive buffer is not valid until such a response is issued.
This response is issued for both common pool and private buffers.

Receive Buffer Unused — When the protocol for a specified tributary is halted, the DMV11 automatically returns all associated private receive buffers to the user program. To do this the DMV11 issues a
buffer disposition response with a type code of 011 for each outstanding buffer held by the specified
tributary. This pertains to private buffers only.
7

BSEL3

BSELS

)

[

TRIBUTARY ADDEESS J

| R

RDO

BsgL7 | B/A|

B/A|

HIGH SIXBITS

)

IEl

|BSELO

CMD TYPE
CODE

BUFFER ADDRESS

RDI

HIGH BYTE

CHARACTER COUNT

17 | 16

IEO

1
{

BUFFER ADDRESS
.

3
|

2
|

LOW BYTE

CHARACTER COUNT
LOW BYTE

BSEL2
SEL2

BSEL4

SEL4

BSELS6

SEL6

18 BIT ADDRESS MODE

6
|§

7
RSEL3

BUFFER ADDRESS
: HIGI-i BYTEl

UNUSED
1

eL11l

)

HIGH SIX BITS

—

22BIT|

MK-16842

IEl

|8SELO

cMD TYPE

|MODE

CODEY

}

S‘E‘Egs

. LOW BYTE

CHARACTER COUNT
4

|BSEL2

|SEL2

BSEL4
SEL4

BUS ADDRESS BITS 16-21
|

BUFFER ADDRESS
. LOWlBYTE .

UNUSED

RDI

—>|
1

CHARACTER COUNT

UNUSED

[

RDO

IEO

l
'

o | R

TRIBUTARY ADDRESS

BSEL7 |

BSEL

—_—

BSELS

BSEL11

SEL10
0

22 BIT ADDRESS MODE
% BUFFER DISPOSITION RESPONSE TYPE CODES:

RECEIVE BUFFER COMPLETE = 000

RECEIVE BUFFER UNUSED =011

3. TRANSMIT BUFFER COMPLETE = 100
4. TRANSMIT BUFFER SENT NOT ACK'd

=110

5. TRANSMIT BUFFER NOT SENT = 111

Figure 3-8 Buffer Disposition Response Format
3-19

K-2515

The DMV11 returns all common pool buffers if the user program issues a request halt state control
command with a tributary address of zero. When all common pool buffers are returned, the DMV11
issues an information response indicating that the process is finished.

Transmit Buffer Complete - When a message is transmitted successfully, the DMV11 notifies the user
program by issuing a buffer disposition response with a type code of 100. Successful transmission
means that the receiving station has acknowledged receipt of the message.

Transmit Buffer Sent But Not Acknowledged — When the protocol for a specified tributary is halted, the
DMV11 automatically returns all transmit buffers currently being processed by that tributary to the
user program. To do this, the microcode issues a buffer disposition response with a type code of 110 for
each buffer sent but not acknowledged.
NOTE
During protocol operation, after seven unacknowledged transmissions of a message occur, the transmit threshold error is exceeded and the DMV11 issues a control response indicating this error (see
Section 3.4.2). The DMV11 continues to retransmit
the message and responsibility for terminating the
transmission belongs to the user program.

Transmit Buffer Not Sent - DMV11 maintains a queue of buffers to be transmitted for each tributary
address established in the network. When the protocol for a given tributary is halted, the DMV11 returns all unused buffers in the associated queue to the user program. To do this, the DMV11 issues a
buffer disposition response with a type code of 111 for each transmit buffer remaining in the queue.

The other CSRs used by the buffer disposition response are BSEL3, SEL4, and SEL6. The function of
these CSRs is as follows:

e
e

BSELS3 specifies the tributary address associated with the buffer disposition response.
SEL4 and bits 14 and 15 of SEL6 contain the 18-bit buffer address for the buffer being

completed or returned. For 22-bit address mode, bits 0-5 of BSEL6 are used with SELA4.
e

SEL6 (or SEL10 in 22-bit address mode), bits zero through 13, compose a 14-bit character

count allowing for a maximum buffer size of 16,383 bytes. A character count returned by a
buffer disposition response is designated in positive binary notation.

Protocol is halted for a tributary in one of three ways when:

3.4.2

The user program issues a control command halting the tributary.

A DDCMP STRT message is received while the tributary is in the run state.

A DDCMP maintenance message is received, temporarily halting the protocol, while receive
buffers are being returned.

Control Response

A control response is an unsolicited response issued by the DMV11 when an error is detected or when
protocol information must be passed to the user program. The format for the control response is shown
in Figure 3-9. BSEL3 contains the tributary address or character count, SEL4 and bits 8 through 13 of
SEL6 contain the bus address for the affected buffer, and BSEL6 indicates the type of information
being passed to the user program. In 22-bit address mode, SEL6 contains buffer address bits 16-21 and
3-20

BSEL10 indicates the type of information being passed to the user program. These types of information
are indicated by an octal code and are listed in Table 3-7. Basically there are four categories of information.

1.
2.
3.
4.

System events
Protocol events
Network errors.
Procedural errors
Table 3-7

Output Codes (BSEL6)

Octal
Code

Category

002

Network
Error

Information

Receive threshold error — This error is reported to the user program when the
number of consecutive receive errors equals seven. These receive error types
are:

Message header blockcheck.

Message data blockcheck.

NAK in response to a DDCMP reply message.

Buffer temporarily unavailable.

Receive message overrun.

Message header format error.

When a message is too long for the

available buffer.

Each time the receive threshold error is reported, the counter is reset to zero.

004

Network
Error

Transmit threshold error — This error is reported when the number of consecutive transmit errors equals seven. These transmit errors consist of four
types and occur when:

A STRT message is transmitted but not acknowledged within the timeout
period.

A STACK message is transmitted but not acknowledged within the
timeout period.
|

ANAKisreceived in response to a transmission with a reason code other
than REP response.

A data message is transmitted but a reply was not received within the
timeout period.

Each time a transmit threshold error is reported, the transmit error counter is

reset to zero, except when remaining in the DDCMP ISTRT and ASTRT
states.

006

Network
Error

Select threshold error — This error is reported when the selection interval timeout counter for a given station has timed out seven times. The selection interval is the time allocated for a tributary to respond to a poll or for a point-topoint station to respond to a transmission.
Each time the select threshold error is reported, the selection error counter is
reset to zero.
|

3-21

Table 3-7

Octal
Code

Category

Output Codes (BSEL6) (Cont)

Information

NOTE

For more information on receive, transmit, or selection threshold errors, see Section 5.3.3.
010

Protocol
Event

Start message received while running — This response indicates that a
DDCMP STRT message was received from the station specified in BSEL3

while this station was in the DDCMP run state.

In normal operation, this méssage is used by a control station to inform a tri-

butary that the control station has started protocol operation for that tributary.
The start message is also used to resynchronize the logical link between a control station and tributary. This might be necessary when message traffic is inhibited because of threshold errors or receive or transmit overruns.

(

When the DDCMP STRT message is received: 1) the DMV11 responds with
start message received while running, and 2) the protocol at the tributary halts
and all buffers are returned.

At this time the logical link may be restarted (request start-up state control

command).

Protocol
Event

014

Protocol
Event

Maintenance message received while running (or ISTRT or ASTRT) — This
response indicates that a DDCMP maintenance message was received by a
specific tributary while it was in the DDCMP run, ISTRT, or ASTRT state.
This causes the tributary to notify the user program, return all unused buffers
to the user program, and halt the protocol. The DMV11 then places the tributary in the maintenance state. The message that caused this event is lost.
Maintenance message received while halted — This response indicates that a
DDCMP maintenance message was received by a specific tributary while it
was halted. This places the tributary in the maintenance state. The message
that caused this event is lost.

016

Protocol
Event

022

System
Event

Start message received while in the maintenance state — This response indicates that a DDCMP STRT message was received by a specific tributary
while it was in the maintenance state. No further action is taken by the microcode. The user program determines what action to take based on this response.
Tributary polling state dead — This response informs the user program at a

control station that the specified tributary polling state has gone to the dead
state.

This response has no meaning in point-to-point networks.

3-22

,//‘m TM~

012

(

Table 3-7 Output Codes (BSELS6) (Cont)
Octal
Code

Category

Information

024

Protocol

Run state — This response informs the user program at all stations that a specific tributary has entered the run state. The DMV11 microcode issues this
response as a result of receiving a request start-up state control command and
having completed the DDCMP start-up sequence.

Event

026

Network

Babbling tributary
— This response is issued to a user program to record the

Error

occurrence of a babbling tributary. Itis only used by half-duplex point-to-point

‘and multlpomt control stations.

A babbling tributaryis one which continues to transmit valid control messages
or message headers beyond the end of a programmable timeout (babbling tributary timeout counter).
The babbling tributary response usually indicates a malfunction at the transmitting station or too short a period for the timeout counter.
Recovery from this error condition generally requires human intervention at
the remote station.

030

Network
Error

Streaming tributary — This response is issued to a user program to indicate
that the remote station failed to release the channel at the end of the selection
interval. It is only used by half-duplex point-to-point and multipoint control
stations.

The streaming tributary timeout period is determined by the programmable
streaming tributary timeout counter. The timeout period starts at the end of
the selection interval.
This error condition generally indicates a modem malfunction at the remote

station or an inappropriate choice of the streaming tributary timeout counter.

Recovery from this error condition generally requires human intervention at
the remote station.

32-76

Reserved

100-276 Procedural
Error

Procedural errors — This response is issued by the DMV11 when the user program violates the procedures designated for interfacing the DMVII. In all
cases, the event that caused the procedural error is ignored by the microcode.
All procedural errors except octal codes 140, 300, and 302 are reported immediately to the user program. Those procedural errors are placed on the response queue. Specific procedural violations are identified by the octal code in
BSELG6 as follows.

3-23

Table 3-7

Octal
Code | Category

Output Codes (BSEL6) (Cont)

Information

Code

Description

100

A command other than a mode definition command is issued before

the mode has been established. Control in with no request will not
return this error. Used for releasing the port.

102

Invalid type code used in a command.

104

Invalid mode change (for example, the mode of a tributary station is
|
changed to point-to-point).

106

A nonglobal command is issued to an unestablished tributary.

110

A nonglobal command is issued having a tributary address of zero.

112

Attempt to delete or place an unhalted tributary in the start or

114

Attempt to establish more than 12 tributaries.

116

Attempt to establish an already established tributary.

120

An invalid request key is used in a control command.

122

Attempt to assign a buffer for an unestablished tributary.

124

Attempt to assign a buffer for a halted tributary

126

300

Procedural
Error

maintenance protocol state.

Attempt to assign a buffer having a byte count of zero.

130

Attempt to assign a transmit buffer with a tributary address of zero.

132

Attempt to write or read and clear a reserved area of a tributary or

134

Attempt to use the reserved bits in BSEL7 of control command.

136

Attempt to return all common receive buffers while the common

140

Attempt to raise the common pool buffer quota to a value higher than

142-276

Reserved

global status slot.

buffer pool is being used.

376 octal.

Buffer too small — This response informs the user program that the assigned

receive buffer is not large enough for the current incoming message. Recovery
from this error condition is detailed in Section 4.6.2.2.

3-24

Table 3-7

Output Codes (BSEL6) (Cont)

Octal
Code

Category

Information

302

Procedural

Nonexistent memory — This response is issued to the user program when the

Error

DMYV11 microcode attempts to access a CPU memory location that does not

respond. The address that caused the error is returned in BSEL4, BSELS, and

BSEL7 for this response.
This error is fatal to the station that initiated the memory access causing the
error. That station must be halted and restarted (see Section 4.6.2.1).

NOTE
With the exception of the buffer too small and nonexistent memory errors, the only control response
fields used by the DMV11

when posting a pro-

cedural error are the type code field in BSEL2, and
the output code field in BSEL6. All other fields remain as set by the user program in the command
that originally generated the procedural error.

304

|
|

System

Modem disconnected — This response informs the user program that an on-to-

Event

off transition of the EIA signal data set ready (DSR) was detected. Such a

transition indicates that the modem is disconnecting from the communications

-N

line.

Since this is a global response, the content of BSEL3 is zero.
When BSEL7=304, modem clear to send failure: (CTS) global response. Informs
user program that CTS failed to set after asserting request to send (RTS), or

CTS has gone from an ON to OFF

306

System
Event

transition while transmitting.

Queue overflow — This response indicates that the free linked list is empty (see
- Section 4.6.2.3).

This error typically indicates that for some reason output responses are being

called for faster than the microcode can process them.

NOTE
This is a global fatal error and the DMV11 initializes itself after attempting to return all informa-

tion (response queue only).

Once this response is issued, the user program has three seconds to retrieve the
next pending response from the CSRs. Three seconds are allowed for each
pending response before the internal microdiagnostics clear the CSRs (see
Section 4.3 for restarting).

310

System
Event

Modem carrier loss — This control response code informs the user program

that the EIA signal carrier detect has gone from on to off while the DMV11
was in the process of receiving a message. Since this is a global response, the
content of BSEL3 is always zero.

3-25

BSELS

TRIBUTARY ADDRESS

COUNT HIGH BYTE

]

*BUS ADDRESS BITS 16-21
14

IEl | BSELO

:
.
—
*BUS ADDRESS OR CHARACTER
COUNT LOW BYTE

22BIT}

RDI MODE CMD TYPE CODE

IEO

RDO

—
—
* BUS ADDRESS OR CHARACTER

BSEL7

BSEL3

o | rRQ

1§

CO.DE

EVENT/ERROR
5

2
3

BSEL4
SEL4

BSEL2

SEL2

BSEL6

SEL6

18 BIT ADDRESS MODE

*ONLY APPLICABLE FOR NON-EXISTENT MEMORY
AND BUFFER TO SMALL ERRORS
MK-2510

Figure 3-9
3.4.3

Control-Out Command Format

Information Response

An information response is issued by the DMV 11 microcode in reply to a request for information by the
user program. The format for this response is shown in Figure 3-10. The type code for this response is
010 binary as indicated in BSEL2. BSEL3 contains the tributary address and SEL4 contains the information requested by the user program. If the information requested is from a GSS, BSEL3 contains a
ZEero.

An information response contains a return key code or a TSS or GSS address in BSEL6 bits 0-4. The
return key codes are used in response to control request keys or protocol events and are encoded as
shown in Table 3-8. The TSS address is used in response to a read or read and clear TSS/GSS command in conjunction with bits 5 and 6 of BSELS6.

Information responses to read or read and clear TSS/GSS control commands, use the TSS address
field (bits 0-4 of BSEL6) to indicate the TSS or GSS location read. Bits 5 and 6 indicate whether the
response is to a read or read and clear input command.
3.5

TSS/GSS ACCESS

When a user program accesses a TSS or a GSS through a control command, the DMV11 reads the
designated location and passes the data to the user program by means of an information response.
Reading a TSS or GSS location results in two bytes of data from that location being stored in BSEL4
‘and BSELS of the information response, with the low-order byte in BSEL4, and the high-order byte in
BSELS. If a TSS is being read, BSEL3 in the information response contains the associated tributary
address. However, data read from a GSS is passed to the user program through an information response
having a zero in BSEL3.

As described in Table 3-5, any TSS or GSS location can be read, and specific locations can be read and
cleared. Along with the TSS/GSS address, BSEL6 in an information response also contains two singlebit fields that indicate a read or a read and clear TSS/GSS. These information response fields are
-'

described in detail below.

TSS/GSS address

Read TSS/GSS
|

This field (BSELS, bits zero to four) contains the octal address of the

"TSS/GSS location from which the data in BSEL4 and BSELS is read.

When set, this bit (BSELS6, bit five) designates that BSEL4 and

BSELS contain the data requested by the read TSS/GSS control com»

mand.

3-26

——

When set, this bit (BSELS6, bit six) designates that BSEL4 and BSELS
contain the data requested by the read and clear TSS/GSS control
command. In addition to reading the requested TSS/GSS location, the
DMV11 also clears that location.

Read and clear TSS/GSS

NOTE
The TSS/GSS locations accessible for writing,
reading, and reading and clearing, are listed and described in Table 3-5.

7
7

—

BSEL3

4
:

|
|

—

]
T

BSEL5

]
|

RQl

1
|

L
!

———

NOT USED

,
13

READ/

CLR

0
|

IEI | BSELO

1
|

[
T

SEL4

——t—
RETURN KEY OR

BSEL6

SEL6

TSS ADDRESS

IBseL2

BSEL4

DATA

Tss {TSS
8

CMD TYPE CODE | gg|
2

1
I

—rt
9

RDI

DATA

—

IEO

RDO
|
!

5
.

TRIBUTARY ADDRESS
i|
|

BSEL7

0
MK-2391

Figure 3-10

Table 3-8
Octal
Code

Name

Information Response Format

Return Keys for Information Response

Description

Return Modem | This code indicates that BSEL4 and BSELS contain the requested modem
Status
status (see Appendix C).

Buffer Return
Complete

This code indicates that the process of returning all buffers is completed.
Buffers are returned to the user program under the following circumstances:

The protocol event STRT message received while running occurred.

This causes all private buffers assigned to the tributary designated by
the address in BSEL3 to be returned.

The protocol event maintenance message received while running
occurred. This causes all private buffers assigned to the tributary
designated by the address in BSEL3 to be returned.

The user programissued a control command containing the request key

The user program issued a global control command (BSEL3 = zero)
containing the request key request halt state. This causes all unused
common pool buffers to be returned.

request halt state causing all private buffers assigned to the trlbutary
designated by the addressin BSEL3 to be returned,

Information responses containing the return key code for buffer return
complete always have zeros in BSEL4 and BSELS.

3-27

CHAPTER 4
PROGRAMMING TECHNIQUES

4.1

INTRODUCTION
Proper design of user programs for operation with DMV11-based multipoint and point-to-point networks requires that consideration be given to a number of programming topics. This chapter discusses
the following programming topics.

Command discipline and handshaking;
DMVI11 start-up;
Criteria for determining user-defined parameters;
Error counter access;
Error recovery procedures;
Booting a remote station.

These programming topics deal with interfacing the user program and DMV11 microcode by using the
DMV11 command/response structure.

4.2 COMMAND/RESPONSE DISCIPLINE AND HANDSHAKING

The command/response interface between a DMV11 and the user program is accomphshed through
the DMV11 CSRs that are addressed through the CPU I/0 page.

Since the DMV11 runs in a multiprocessing mode with the associated CPU, the passing of commands
and responses through this interface must be highly disciplined to eliminate the possibility of a race
condition (the user program setting bits in the CSRs after the microprocessor has read those bits). This
interface discipline requires that the user program follow two separate procedures; one for issuing commands, and one for retrieving responses.
Figure 4-1 illustrates the control bits involved in CSR interface discipline. These bits are located in the
DMV11 CSRs BSELO and BSEL2. Examination of Figure 4-1 shows that BSELO contains two control
bits named interrupt enable in (IEI) and interrupt enable out (IEO), bits zero and four respectively.
These bits when set, serve to enable the microprocessor to interrupt the main CPU under two circumstances:

When the CSRs become available for the issuing of a command after access is requested by
the user program for that purpose (IEI and RDI).

When the microcode has a response to be retrieved from the CSRs by the user program (IEO
and RDO).
NOTE
Interrupt mode must be used, otherwise,

receive

overruns and transmit underruns are very probable.

4-1

NOTE

It is recommended that the interrupt enable (IEI
and IEO) bits be set when interfacing with the
CSRs. It is imperative that they be set when
operating at S6K b/s because the microprocessor
is halted momentarily on every access to the
CSRs.

The procedures described below defining CSR interface discipline are based on operation in the interrupt mode. As a consequence, the IEI and IEO bits should be set by the user program prior to using the
CSR interface.

RQl
RDO

IEO

IEI | BSELO

RDI

BSEL2
MK-2390

Figure 4-1 CSR Interface Control Bits
4.2.1

Command Discipline

At start-up time, before the user program can execute any command, it must initialize the DMV11.
This is accomplished by the program setting the master clear bit in BSEL1 and waiting for the DMV11

gram in two successive steps. The first step requests the use of the data port. The second step identifies
the command type and the data port information for the appropriate command, and notifies the
DMV11 that the command is in the CSRs. The specific content of each data port is further defined
under each command description in Section 3.3. The handshaking procedure for input commands is as

Once the DMV11 is initialized, commands may be issued. All commands are issued by the user pro-

’//‘“”“"\v

to set the run bit.

follows (see Figure 4-2).

The user program requests the use of the data port to issue a command by setting request in
(RQI) bit 7 of BSELO. The user should also set bit 0 of BSELQO, interrupt enable in (IEI), at
the same time (using the same instruction) to allow the DMV11 to interrupt the CPU when
the data port is available. An interrupt is generated to XX0 when RDI is asserted by the
DMV11.

NOTE

The 22-bit mode is used when the software supports
22-address bit buffers. A “one” in bit 3 of BSEL2
indicates to the DMV11 that the software supports
the change in the command format required to support 22-address bits.

When the data port is available, the DMV11 informs the user by setting ready in (bit 4 of
BSEL2) and generating an interrupt to vector XXO.

If a single command is to be issued, the user program clears RQI. If a series of commands
are to be issued, RQI can remain set until just prior to the loading of the last command into
the CSRs. By leaving RQI set while issuing a series of commands, the user program is assured of having access to the CSRs after the next response.

4-2

//,m»\\

On detecting RDI bit set, the user can: 1) load the appropriate information into SEL4 and
|
SEL6, and 2) load the input command code into bit 0-2 of BSEL?2.

4.2.2

Retrieving Responses

The DMV11 issues responses in two steps. If RDI is not set, the data pertinent to the responses being
issued is loaded into BSEL3, SEL4, and SEL6. Once this is complete, the DMV11 sets the ready out
(RDO) bit and the command code in BSEL2. An interrupt through vector XX4 is generated if the IEO
bit is set. Generally, processing an output response involves the following steps:

The user program checks for RDO set. This is done by waiting for an interrupt.

To use the output interrupt capability, the user program must set the output interrupt enable
bit in BSELO immediately after it detects that the run bit has been set following master
clear.

When an RDO set condition is detected, the user program should move the contents of
SEL2, SEL4, and SEL6 into a working storage area and clear RDO in BSEL?2 as soon as

possible. When RDOis cleared, the data port (SEL4 and SEL6)is released to the DMVI11
for more input or output processing.

4.2.3

CSR Interface Interactions

User-program access to the CSRs is under complete control of the DMV11 microcode. Access to the
CSRs is granted upon request when the user program has a command to issue, or when the microcode
has a response for the user program. Figure 4-2 illustrates the nature of the access window available to
the user program under interrupt control, when issuing a command, or retrieving a response. As previously indicated, the user program requests use of the CSRs for the purpose of issuing a command by
setting RQI. The DMV11 microcode makes the CSRs available for the issuing of a command, only
when it is not using them, by setting RDI and interrupting the user program through the floating vector
XXO0. As a result, the time perlod between the setting of RQI by the user program and the granting of
the CSRs through an interrupt is indeterminate.

When commands are being issued from a queue, and the last command has been issued with the user
program still having ownership of the CSRs (RDI is set), there is a mechanism for returning the CSRs
to the DMV11. In such cases, the user program can issue a control command with the code for no
request in the request key field, thereby, signalling the microcode to ignore the contents of the CSRS
In this way, the possible reading of erroneous data by the DMV11 microcodeis avoided.

If the user program is to issue a single command, RQI should be cleared prior to issuing the command
to the CSRs, as indicated in Figure 4-2. However, if a series of commands are to be issued, the user
program can leave RQI set. In this circumstance, when a command is issued and RDI is cleared, the
microcode relinquishes the CSRs to the user program as soon as they become available. The time period between clearing RDO upon completing one command, and an interrupt initiating the next command, is also indeterminate.

When the DMVI11 has a response to be passed to the user program, it sets RDO then interrupts the
main CPU through the floating vector XX4. At this point, the user program has ownership of the CSRs
and can proceed by reading the response. Once the response is read from the CSRs, the user program
should immediately clear the RDO bit. User-program routines responsible for issuing commands and
retrieving responses should limit the CSR access time required to load a command or retrieve a response.

4.3

DMV11 START-UP

Starting a DM V11 requires that the user program perform a series of steps to; 1) configure the DMV11
to operate within the context of the associated network, 2) establish user-defined parameters, and 3)
initiate protocol operations at the DMV11.

4-3

ral

USER CLEARS RQl

USER
SETS

NO FURTHER COMMANDS

l TO ISSUE

*DMV11
SETS

RDI

USER HAS TOTAL CONTROL OF CSRs | 1AS BEEN ISSUED

TO ISSUE COMMAND

(IE)

*¥ USER CLEARS RDI TO
NOTIFY DMV11 THAT COMMAND

¥DMV11
SETS
RDO

(IEO)

USER HAS TOTAL CONTROL OF CSRs

% USER CLEARS RDO TO
NOTIFY DMV11 THAT

RESPONSE HAS BEEN RETRIEVED

TO RETRIEVE RESPONSE

* DMV11 HAS OWNERSHIP OF CSRs
MK-2514

Figure 4-2
4.3.1

CSR Access Window

Configuration Procedure

The sequence to configure a DMV11 control and tributary station for network operation is formed by
the following steps:
1.

Set the master clear bit and wait for the run bit to set. (See Section 3.3.1).

When the run bit is set, read BSEL4 and BSELS6.

If the contents of BSEL4 equals octal 33, and the contents of BSEL6 equals octal 305, the
start-up diagnostics have successfully executed and the DMV11 is running. Any other value
in BSEL6 indicates that an error condition was detected by the start-up diagnostics. The values and meanings of these diagnostic error codes are listed in Table 4-1.

If the DMV11 operational mode is software selectable, set the mode for that device by issuing the appropriate mode definition command (see Section 3.3.2). If the mode for the
DMV11 is selected by internal switches, this step can be ignored.
4.3.2

Specifying User-Defined Parameters

After a DMV11 is configured, the user parameters are specified. User-defined parameters include parameters used by the polling algorithm, and parameters specific to protocol operation. In addition,
those user parameters that are specific to the operation of tributaries, are stored in the tributary status
slot (TSS) associated with each tributary. Parameters that are pertinent to overall system operation are
stored in the global status slot (GSS) for the control or tributary station.

4-4

Table 4-1

Diagnostic Error Codes

BSELG6

BSEL4

Description

101

N/A

Branch test has failed and the microcode is spinning in a loop.

102

N/A

6502 internal resister test has failed and the microcode is spinning in a loop.

103

N/A

Load and store instructions test has failed and the microcode is spinning in a

loop.

104

N/A

Compare instructions test has failed and the microcode is spinning in a loop.

105

N/A

Increment and decrement instructions test has failed and the microcode is
spinning in a loop.

106

N/A
|

Shift and rotate instructions test has failed and the microcode is spinning in
a loop.

107

N/A

Logic instructions test has failed and the microcode is spinning in a loop.

110

N/A

Add with carry, subtract with carry, set and clear decimal mode instructions test has failed and the microcode is spinning in a loop.

111

- N/A
‘

Stack push and pull instructions test has failed and the microcode is spinning in a loop.

112

N/A

Subroutine instructions test has failed and the microcode is spinning in a
loop.

113

N/A

Ram scratchpad, CSR, and NPR address resisters addressing test has failed
and the microcode is spinning in a loop.

114 -

N/A

Ram scratchpad, CSR, and NPR address resisters data test has failed and
the microcode is spinning in a loop.
|

115

N/A

True interrupt test has failed and the microcode is spinning in a loop.

116

N/A

Ram data and addressing test has failed and the microcode
is spinning in a
loop.

117

N/A

Ram alternating data test has failed and the microcode is spinning in a loop.

120

N/A

121

N/A

Line unit message test has failed and the microcode is spinning in a loop.

305

The microdiagnostics have completed without errors.

Indexed indirect addressing mode instruction test has failed and the micro-

code is spinning in a loop.

As described in Section 3.3.3, user parameters are specified through control commands configured to
address a TSS or a GSS. These control commands write the data contained in BSEL4 and BSELS into
the locations specified by bits 0-4 of BSEL6 (TSS or GSS address). In establishing polling and protocol
parameters, the user program has the option of accepting the default for a parameter or setting the
parameter to some predetermined value. Chapter 5 details the criteria to be used in determining optimum values for the various polling parameters. Criteria for determining the remaining parameters,
which generally concern the operation of the communications link, are presented in Section 4.6.
NOTE

Although the majority of user-defined parameters
are 16-bits in length, some are single byte parameters. If the user program wishes to change one of the
single-byte parameters and accept the default for the
other, both parameters must be written. This is necessary because both TSS and GSS user-defined parameters are written on 2-byte boundaries.

The process of establishing user-defined parameters is presented as two separate steps:
Specifying user-defined parameters for control and tributary station TSS structures.

Specifying user-defined parameters for control and tributary station GSS structures.

structures at a multipoint control station is listed below:

Issue a series of control commands to set the value for the transmit delay timer. This is referred to as the preset value.

Issue a series of control commands to establish the polling parameters Q and R for the three
polling levels.

Issue a series of control commands to specify values for the active, inactive, unresponsive,
and dead polling state-change parameters.

Issue a series of control commands to specify values for the maximum transmitted message
count.

Issue a series of control commands to set the selection timers for tributaries (or issue a single

command to set the point-to-point station reply timer).

Issue a series of control commands to set the babbling tributary timers.

4-6

4.3.2.1 Specifying TSS Parameters — TSS parameters that can be specified by the user program are
listed in Table 4-2 by name, BSEL3 address, size, and default value. A functional summary of each
parameter is also given. The actual order of setting TSS parameters through appropriately configured
control commands is arbitrary. The complete command series to specify these parameters for TSS

"/,@a,\ .

Table 4-2

TSS Addr (Octal)

Name

BSELSG

XDT
PRESET

230

User-Defined TSS Parameters

Size
(Bits)

Default
(Octal)

Description

Preset value for
the transmit delay
timer. This parameter provides a
fixed delay between
transmission of data
and maintenance
messages. The de-

fault value of 0 =

Q (Active)
Q (Inactive)
Q (Unresp)

231

232
233

o0 OO OO

no delay.
377

The initial value of
polling urgency (U)
for the tributary:
The TSS for a tribu-

R (Active)
R (Inactive)
R (Unresp)

231
232
233

o0 O0 OO

tary must be assigned a Q value for
each of the three
activity levels;
active, 1nactive,
and unresponsive.
This parameter is
applicable only to
TSS structures at
the control station.

100
20

The rate (R) by
which the urgency

(U) is increased for
- the tributary.
The TSS for the tributary must be
assigned an R value
for each of the
three activity
levels; active, 1nactive, and unresponsive. Both the
Q and R for a given
tributary are es-

tablished through a
single control command. Therefore, if

4-7

Table 4-2

User-Defined TSS Parameters (Cont)

TSS Addr
Name

(Octal)
BSEL6

Default
(Octal)

Size
(Bits)

Description
one parameter 1S to

be set to a unique
value, and the default 1s to be ac-

cepted for the
other, both the default value and the
unique value must be
written. This parameter 1s applicable
only to the TSS
structures at the
multipoint control
|
station.

NDM-INACT

234

Number of no data
messages required to
go inactive: This is

the number of consecutive polls to be
made (without receiving a data message) before changing the activity

level of that tributary from active to
inactive. This parameter 1s applicable
only to the TSS

structures at the
control station.
Number of timeouts

234

to go unresponsive:
The number of consecutive polls of a
tributary (without
response) before
changing the activity level of that
tributary from active or inactive to
unresponsive. Both
the NDM-INACT and
TO-UNRSP counts are
established through
a single control

4-8

TO-UNRSP

Table 4-2 User-Defined TSS Parameters (Cont)

Name

TSS Addr
(Octal)
BSELS6

Size

(Bits)

Default
(Octal)

Description

command. Therefore,
if one parameter is

to be set to a
unique value, and
the default is to be
accepted for the
other, both the default value and the
unique value must be
written. This parameter 1s applicable
only to the TSS
structures at the

multipoint control
station.

TO-DEAD

235

Number of timeouts

to go dead: The number of consecutive
polls of an unresponsive tributary
(consecutive selection timeouts) before the activity
level of that tributary is changed from
unresponsive to
dead. This parameter is applicable
only to the TSS
structures at the
multipoint control
station.

MXMC

235

Maximum transmitted

message count: This
parameter is a count

of the maximum num-

ber of abutting data
messages to be
transmitted by a
station before it
deselects itself.
This count applies
to the TSS structures at both control and tributary

Table 4-2

TSS Addr

Name

(Octal)

User-Defined TSS Parameters (Cont)

Size

(Bits)

BSELG6

Default

(Octal)

Description
stations in multipoint networks as
well as point-to-

point stations. Both
TO-DEAD and MXMC
for a given tributary are established
through a single
control command.
Therefore, if one
parameter is to be
set to a unique
value, and the de“fault is to be accepted for the
other, both the
default value and
the unique value
must- be written. At
tributary and pointto-point stations,
the polling parameter TO-DEAD is ignored.

SEL
TIMER

236

3 (seconds)
(454 Octal)

Selection interval
timer: This timer

- 1s started when a
message 1s transmitted with the
select flag set, and
halted when a valid
reply is received or
the line is resynchronized. The selec-

tion timer is used
as a reply timer for
full-duplex pointto-point networks
(see Section 4.4.1).
It is used as the
select timer at multipoint control stations, and in halfduplex point-topoint networks. This

Table 4-2

User-Defined TSS Parameters (Cont)

TSS Addr

|
Name

(Octal)
BSEL6

Size
(Bits)

Default
(Octal)

Description

counter counts in 10s
of milliseconds (ms)
from 10 to 655,350 ms.

BAB
TIMER

237

6 (seconds)
(1130 Octal)

Babbling tributary
timer: This timer
is used to detect
a babbling tributary (see Section |
442). Ina
multipoint network
this parameter is
applicable only to
the control station.
However, this para-

meter 1s applicable
to both stations in
point-to-point networks operating

half-duplex.

4.3.2.2 Specifying GSS Parameters — As previously indicated, when one or more tributary addresses are
established at a DMV11, the DMV11’s microcode automatically creates a GSS for that control or

tributary station. The GSS parameters that can be specified by a user program are listed in Table 4-3 by
-

name, BSEL3 address, size, and default value. A functional summary of each parameter is also given. If a
- valueis not spemfled for a parameter the microcode uses the default value. Specifying a user-defined GSS
parameter requires that BSEL3 in the pertinent control command contain zero. The controlcommands
necessary to specify GSS parameters for a multipoint station are listed below:
1.

A control command to specify the number of sync-characters (NUM SYNC) that are to precede nonabutting transmit messages.

A control command to set the streaming tributary timer.

Three control commands to establish values for the global polling parameters delta time
(DELTA T), dead tributary (DEAD T), and poll delay, respectively.

Specific user-defined TSS and GSS parameters are common to both control and tributary stations.
Note that control commands specifying TSS parameters must have the address of the tributary associated with the TSS being accessed in BSEL3. Similarly, each control command specifying a GSS parameter must have BSEL3 set to zero. Since the prior steps have covered user-defined TSS and GSS

4-11

parameters (see Table 4-2 and 4-3) at the control station, the two steps listed below complete the parameter-spemfymg process at the tributary stations:

Issue a series of control commands at each tributary station to set the maximum transmitted
message count (MXMC) for each active TSS in a tributary station TSS structure. Note that

the 8-bit value for MXMC must be placed in BSELS of each command (the tributary station
microcode ignores BSEL4 in these commands). The procedure for determining an optimum
value of this parameter for tributary stations is the same one used for control stations.
Issue a single control command at each tributary station to set a value for the number of
sync-characters (NUM SYNC) that are to precede nonabutted transmit messages. The procedure for determining an optimum value of this parameter for tributary stations is the same
one used for control stations.

User-Defined GSS Parameters
S

Table 4-3

Name
NUMSYNC |

GSS Addr
(Octal)

Size

Default

BSEL6

(Bits)

(Octal)

233

Description

12 (low

Number of sync-characters:

speed)
17 (high
speed)

This global value specifies the number of synccharacters that are to
precede nonabutting transmitted messages. This
parameter applies to all

stations. Low speed is
defined as less than 19.2K

b/s and high speed is 19.2K
and above b/s.
STREAM
TRIB

234

6 (sec.)
(1130

Streaming tributary timer
preset: This timer is used

Octal)

to detect a streaming tributary (see Section 4.4.3)
and Table 3-7). In a multipoint network, this
parameter is applicable
only to the control station. However, in pointto-point networks, this
parameter is apphcable to
both stations.

DELTA T

235

200 (ms)

(24
Octal)

Delta time: This is the

polling algorithm update
increment. This global
parameter, which is applicable only to multipoint control stations,
is used by the polling

Table 4-3

User-Defined GSS Parameters (Cont)

GSS Addr

Name

(Octal)
BSEL6

Size
(Bits)

Default
(Octal)

Description
algorithm to calculate
polling urgency (see

Section 5.2.1). The default value of 200 ms is
the minimum value for this
parameter. DELTA T is also
used as the interval for

~updating the transmit
delay timer.
DEAD T

236

10 (sec.)

Octal)

POLL
DELAY

237

Dead timer: This is the

(1750

0 (no
delay)

interval between polls for
dead tributaries. This
global parameter applies
only to multipoint control
stations.
This parameter provides
for a fixed delay between

."/‘

polls for all tributaries
in a network. If the default 1s accepted, the
next poll for any tributary occurs immediately
following the current
poll.

4.3.3 Protocol Operation
At this point the DMVI11 has been conflgured for operation in the associated network andis ready for
protocol operation. The steps required to initiate protocol operation are:

Place established tributaries in the ISTRT state by issuing one control command containing
the request key. Request ISTRT state for each tributary address.

If the DMVI11 is a station in a point-to-point network, one control command must be issued
containing the request ISTRT state request key with a tributary address of one in BSEL3.

The DMVI11 confirms that the protocol is operational at each tributary by issuing a control
response (one for each control command issued) containing the protocol event code for
DDCMP run state entered.

4.4 CRITERIA FOR DETERMINING COMMUNICATIONS LINK PARAMETERS
User-defined TSS and GSS parameters fall into two categories: polling parameters that provide for
user-program control over the dynamic activity of the polling algorithm, and communications link pa-

4-13

rameters that provide the user program with the ability to regulate data traffic over the physical communications line. Referring to Tables 4-2 and 4-3, the communications link parameters include:
Selection interval timer,
Number of sync-characters,
Babbling tributary timer,
Maximum transmitted message count,
Streaming tributary timer,
Transmit delay timer.

Values for the selection interval timer and the number of sync-characters are interrelated, as are values
for the babbling tributary timer and the maximum transmitted message count. These interrelated parameters are described in Sections 4.4.1 and 4.4.2.

4.4.1 Setting the Selection Interval Timer
The function performed by the selection interval timer at a DMV11 depends on the mode selected for
that DMV11. In full-duplex point-to-point networks, this timer is used as-a reply timer for the purpose
of message accountability. This timer serves as a selection interval timer when the mode for the associated DMV11 is one of the following:
e
e
e

A full-duplex control station;
A half-duplex control station;
A half-duplex point-to-point station.

Link management is the process of controlling the transmission and reception of data over networks
where there are two or more transmitter/receiver devices actively connected to the same physical communications link. This applies to half- and full-duplex multipoint networks as well as half-duplex pointto-point links. On half-duplex links, only one transmitter can be active at any time, and on full- duplex
links, only one slave transmitter can be active at a time.

A station on such links can transmit when it is selected or granted ownership of the link. Link ownership
is passed through use of the select flag in the DDCMP message header. Detecting a select flag in a
received message allows the receiving station to transmit after message reception is completed. Sending
a select flag means that the transmitting station ceases transmitting after the current message is sent.

A selection timer detects the loss of a select flag by timing the interval required to receive the longest
message from a station. A timer is started when a station is selected and reset when valid messages are
received from that station. When the timer interval is exceeded at the sending station (a message was

not received during the perlod of the timer) it is assumed that messages with the select flag were either

transmitted or receivedin error.

At this point, the station that originally sent the messages with the select flag set assumes ownership of
the link. This station resumes transmitting as if it had received a valid select return.
The values assigned to select interval timers at stations in half-duplex point-to-point networks should be
different at both stations to avoid possible deadlock race conditions. For both multipoint control stations
and half-duplex point-to-point stations, the criteria for determining the value for a select timer includes
such factors as:
Maximum message length;
Number of sync-characters;
Line speed;
Line turnaround time;
Message processing delays.

4-14

TM~

In this capacity, it performs the link management function and provides for message accountability.

As indicated in Table 4-3, the GSS parameter number of sync-characters has two defaults; one for lowspeed operation (10), and one for high-speed operation (15). The operational speed range of a DMV11 is

specified by the line unit low-speed/high-speed switch which is placed in the appropriate position when the
DMV 11 is hardware configured (see Section 2.5). In the low-speed position the DMV 11 can operate at line
speeds up to 19.2K b/s, and in the high-speed position the device line speed is 19.2K and greater b/s. It is
recommended that the default for the appropriate line speed range be taken for this parameter.
Some recommended values for a selection interval timer are given in Table 4-4. The calculations shown
in Table 4-4 include the following overhead factors:
256 bytes of data
28 bytes of header, sync, and pad characters

Total

284 bytes

The formula used to derive the values listed in Table 4-4 is:
8 bits per byte
X

284 bytes per message + RTS/CTS delay = Timer value (in seconds)

baud rate (bits

per second)
NOTE
Most modems include an RTS/CTS delay that must
be included in the calculation of the value for the se-

lection interval timer. When operating with an external (EIA) modem, the typical delay used is 150 ms.
The delay used when operating with the integral
modem is 100 us.

Table 4-4

Recommended Selection Interval Timer Values

Bits Per Second

Calculated Timer Value for a 256 Byte Message

4 8K

473 ms + 150 ms = 623 ms (700 ms)

9.6K

236 ms + 150 ms = 386 ms (400 ms)

56K

40.5 ms + 0.1 ms = 40.6 ms (50 ms)

The values listed in Table 4-4 represent absolute minimums. In most cases, specific applications require
additional delay time over these values to prevent a timeout during reception of a valid message. Requirement for additional delay time can be caused by processing delays that occur when receiving from
a non-DMV 11 device, or by line delays encountered when dealing with satellite networks. When determining this value, keep in mind that it represents the time the system can reasonably expend waiting for
a response from another station.

When used as a reply timer, the selection interval timer sets the maximum waiting period between sending a message and receiving an acknowledgement before taking error recovery actions. This timeout is
necessary to recover from outages and the distortion of messages by the link. This timeout also prevents
the protocol from being deadlocked.

4-15

The same criteria used to determine a value for a selection interval timer in multipoint networks, are
also used to determine a value when this timer is used as a reply timer.
As shown in Table 4-2, the
default value for both cases is three seconds.

4.4.2

Setting the Babbling Tributary Timer

This user parameter is applicable to half-duplex and full-duplex multipoint network control stations. A
babbling tributary is a tributary that continues to transmit valid DDCMP messages after a programmable
timeout has expired, thereby, denying equal access to other nodes. This situation is controlled by the
babbling tributary timer which monitors the total time period a tributary continuously transmits without
relinquishing the communications line. When this period exceeds the timeout period of the babbling
tributary timer, the user program is notified through a control response. The control response contains the
code for a babbling tributary along with the identity of the offending tributary. When a babbling tributary
is detected, the control station takes no action beyond this notification.

A major consideration in determining a value for the tributary timer is the total time interval that a
given tributary requires to end a selection interval. Determining the value for this timer is similar to
that for the selection interval timer because the same range of factors are used as criteria for calculating the value. The main difference in the two determinations is that the total number of message

bytes should be used in babbling tributary timer parameter calculations rather than the number of
bytes in the longest message.

A value for the maximum transmitted message count parameter must also be considered in conjunction
with the parameter for the babbling tributary timer. The user-defined parameter to set this counter
places a limit on the number of messages that a tributary can transmit during the selection period. This
is done by forcing the select flag when the count of messages received from a tributary equals the value
of the maximum transmitted message count. This count relieves the user program from having to limit
the number of messages queued for transmission in order to avoid a babbling tributary condition.

In any case, the period established
for the timeout of a babbling tributary timer should be long enough

to ensure that timer expiration definitely indicates an error condition. In addition, the parameter assigned to the maximum transmitted message count should also be considered when establishing the period of the babbling tributary counter.
4.4.3 Setting the Streammg Tributary Timer
A streaming tributaryis a tr1butary station on a multipoint line (or an associated point-to-pomt station)
that continues to assert the carrier signal on the link after it has relinquished ownership of the link. In
normal operation, ownership of the link is returned to the control station when it receives a select flag or
the period of the selection interval timer is exceeded. A timeout of the streaming tributary timer indicates a potential jamming of the link by a defective tributary station, a defective point-to-point sta- tion, or a malfunctioning modem.

secondis sufficient.

me—
e

Determination of a value for the streaming tributary timer requires consideration of such factors as
settling time of the communications line and modem delays. As with determining periods for the selection interval timer and the babbling tributary timer, the period specified for this timer should be long
enough to preclude premature expiration of the tlmer For most network applications the default of one

The streaming tributaryis started when ownershlp of the linkis granted to the control station by the
remote station, and stopped when the carrier is dropped by that station. When a streammg tr1butary is
detected, through expiration of the streaming tributary timer, the user program is notifiedin the same
manner as with a babbling tributary. The control station does not transmit until the carrier is dropped.

4.5

ERROR COUNTER ACCESS

The DMV11 is equipped with a large compliment of error counters designed to isolate a wide range of
error conditions. The TSS for each established tributary contains seven error counters along with three
statistical counters that provide background information for error analysis. In addition, the GSS at each
station contains four error counters that tabulate errors that are global to the station. The three TSS
statistical counters are 16 bits in length, and the threshold error counters are three bits in length. The
remaining TSS/GSS error counters are eight bits long.
Reading the Counters

4.5.1

Both TSS and GSS counters are accessed through an appropriate control command with the content of
the requested counter or counters being returned through an information response (see Sections 3.3 and
3.4). Through the control command, the user program has the option of reading, or reading and clearing
the counters. When doing error analysis it is recommended that a user program read and clear these
counters to assure a zero-base for subsequent sampling of the counters. If copies of the counters are
being maintained in main CPU memory, it is also recommended that counters be read and cleared.
NOTE
The three-bit threshold error counters are automat-

ically reset when the maximum count is reached so
that access to these counters is restricted to reading
only.

The DMV 11 error and statistical counter structure is designed to be complimentary. As an example of
this complimentary structure, consider the data errors inbound counter and the data messages received
counter. The data errors inbound counter tabulates the errors related to the validity of message reception such as block-check errors, whereas, the data messages received counter records the total number
of messages received. A ratio of message reception errors to total number of messages received can be
derived from these two counters.
Counter Skew

4.5.2

When performing error analysis, there is a potential of skew between counts due to read time lags and
the requirement that counters be read one at a time. The probability of skew between counts is a function of line speed; the higher the line speed, the greater the probability of a skew condition. An example
of this potential skewing is the possible discrepancy between the number of selection intervals and the
number of selection timeouts. A skew could result from additional selection timeouts occurring while
the counters are being read.

If circumstances require that error/statistical counters be read without the potential for skew, this can
be done by halting the protocol at the tributary. With the protocol halted, the contents of the error/statistical counters in a TSS and in the GSS are frozen at the counts recorded when the protocol
was halted. The counters can then be read without the problem of skew due to read time lags.
4.6

ERROR RECOVERY PROCEDURES

Within a DMV11-based network, there are three basic levels of error recovery involving the user pro-

gram:

Procedural violations where only the user program is notified.

Recovery from errors requiring protocol shutdown initiated by the user program.

Fatal errors resulting in system shutdown with minimal notice to the user program.

Referring to Table 3-7, procedural error codes from 100 to 140 are reported to the user program with

no recovery required. The remaining two procedural errors (codes 300 and 302) involve error recovery

levels two and three respectively. All network errors require recovery through protocol shutdown, and

the control response (queue overflow) could result in network shutdown.
4-17

4.6.1

Recovery from Network Errors

In all cases, recovery from network errors requires that the protocol be halted at the tributary or station

recording the error. Two similar but separate procedures are recommended for recovery from threshold
errors, and babbling and streaming tributary errors. These recovery procedures are described below.

4.6.1.1

Recovery from Threshold Errors - DMV11 threshold errors are detailed in Section 5.3.3. The

recommended recovery procedure to be initiated by the user program at the station recording the errors
is presented below:
1.

Halt the protocol (see Table 3-6).

Read the error counters to determine the nature and cause of the threshold error condition. If
the error results from a shortage of receive buffers, correct the condition. If the transmit or
selection threshold is being exceeded, check the operational condition of the remote station.

When the conditions causing the errors have been eliminated, restart the protocol (see Sec-

tion 4.3.3).
4.6.1.2

Recovery from Babbling and Streaming Tributary Errors — Babbling or streaming tributary er-

rors are created when their respective timers are exceeded. Therefore, a timeout can result from an
actual error condition, or because the period of the timer is too short for the type of message activity on

the line (see Sections 4.4.2 and 4.4.3). A suggested recovery procedure to be used when encountering

these conditions is:
1.

Halt the protocol.

Check the value of timer parameters and increase if the value is not appropriate.

Restart the protocol (see Section 4.3.3).

If this error condition persists, reconfigure the station as specified by Section 4.3.1.

When the cause of the timeout originates at the remote station, action must be taken at the
remote station to ascertain and correct the fault. The local station is at fault only if the values
of the timer parameters are inappropriate.

4.6.2
Recovery from Procedural Errors
The three procedural errors that require a recovery procedure are:
1.

Nonexistent memory error.

Buffer too small error.

Queue overflow error.

The recovery procedure for each of these errors is detailed in Sections 4.6.2.1 through 4.6.2.3.
4.6.2.1
Recovery from a Nonexistent Memory Error — Nonexistent memory errors occur when the
DMV11 tries to access an allocated receive or transmit buffer having an invalid bus address. When this
error is detected, the DMV11 posts a control response to the user program containing the invalid ad-

dress (see Section 3.4.2). It is up to the user program to determine whether the nonexistent address
concerns a transmit or receive buffer.

NOTE
Depending on microcode processing circumstances,
the nonexistent memory address returned to the user
program could have been incremented to the next se-

quential location.

4-18

The suggested recovery procedure for this error is as follows:
1.

Halt the protocol for the tributary or station recording this error to initiate return of all outstanding buffers.
If the error concerns a buffer from the common pool, the user program should issue the global halt command to initiate return of all outstanding receive buffers from the common pool.

Restart the protocol and reallocate buffers as necessary.

Persistent recurrence of this error indicates a possible main CPU or DMV11 malfunction.
NOTE
If the network line speed is 56K b /s, the requests for
retransmission generated by a nonexistent memory
address can result in the overflow of the DMV11 response queue causing a fatal system error (see Section 4.6.2.3).
4.6.2.2

Recovery from a Receive Buffer Too Small Error - When the DMV11 receives a message, it
first checks for the availability of a buffer from the common buffer pool linked list, and if one is available, it uses that buffer. If the common buffer pool is empty or not enabled, the private buffer linked
list 1s checked. If a private buffer is not available, the receiving station NAKs the incoming message.
The steps taken by the DMV 11 microcode in this process are listed below.
|
1.

Is the message number in sequence? Yes, continue; No, ignore message.

Is the common buffer pool enabled? Yes, continue; No, go to Step 6.

Is the common buffer pool quota = 0? Yes, go to Step 6; No, continue.

Is a common pool buffer available? Yes, continue; No, go to Step 6.
Is the common pool buffer too small? Yes, go to Step 8; No, use this buffer.
[s a private buffer available? Yes, continue; No, send NAK — buffer temporarily unavailable.
Is private buffer too small? Yes, send NAK — buffer too small; No, use this buffer.

Is private buffer available? Yes go to Step 7; No, send NAK - Buffer too small.
NOTE
The DMV11 does not scan the common pool or private linked list structures looking for a buffer of sufficient size. Rather, it uses the next available buffer
from the list.

Buffer too small errors apply only to receive buffers. The procedure for recovery from this error is
dependent on whether the allocated buffer is from the common pool or is a private buffer. The applicable recovery procedures are explained below.
A.

Common pool buffer too small
1.

Assign a private buffer of sufficient size to the receiving tributary through a buffer address/character count command (see Section 3.3.4).

4-19

Both private and common pool buffers too small

Halt the protocol for the offending tributary to initiate return of all outstanding private buffers.

Restart the protocol.

Assign a private buffer of sufficient size to the receiving tributary through a buffer address/character count command (see Section 3.3.4).
|

Private buffer too small, and common pool not enabled

If buffers from the common pool are available to other tributaries, and are of sufficient size,
enable common pool buffers for this tributary (see Section 3.3.4).

If the common buffer pool is not in use for other tributaries, follow recovery procedure B
above.

4.6.2.3

Recovery from a Queue Overflow Error — This error is always fatal to the DMV11 recording

the error since it forces automatic shutdown of the device. The basic cause of this error is the inavailability of link blocks from the free linked list (see Section 5.4.1.1). Typically, this error results
when the internal response queue overflows because the DMV11 generated responses faster than the
user program could retrieve responses from the queue. This error can also occur if an inordinate number of receive buffers have been allocated. One cause of response queue overflow is the occurrence of
repetitive nonexistent memory errors in high-speed networks (see Section 4.6.2.1).

When this error occurs, the DMV11 posts the most current entry in the response queue to the user
program. The user program then has three seconds after being interrupted to retrieve the response. If it
is retrieved during this three second window, the next response is posted. As long as the user program
retrieves each response within this window, the process continues until the internal response queue is
empty. These responses can then be analyzed to determine the cause of the queue overflow.
After the last response has been posted, or the three second response period has expired the DMV11
shuts itself down. At this point, returning the DMV11 to operational status requires that the start-up
procedure be initiated from the beginning (see Section 4.3).

4.7

BOOTING A REMOTE STATION

DMV 11-based networks provide the user program, at the multipoint control station or point-to-point
station, with the ability to boot the main CPU at a remote station that has been shut down due to power
outage or software malfunction. There are three ways this boot function can be performed:

Remote load detect: The control station starts the primary MOP boot procedure for a remote
station.

Power-on boot: The first poll received after power-up at the remote station causes the

Invoke primary MOP: The user program at the remote station causes the DMV11 to request
that the control station start the primary MOP boot procedure.

DMVI11 at that station to request that the control station start the MOP boot procedure.

4-20

NOTE
Control station is either a multipoint control or
point-to-point station that is transmitting (over the
link) the boot or requested program to the remote
station. Remote station is either a multipoint tributary or point-to-point station that is receiving
(over the link) the boot or requested program.

NOTE
Power-on boot, remote load detect, and invoke
primary MOP are not mutually exclusive. All three
features could be used in a particular application.
Primary MOP boot procedures require that the DMV11 be switch-configured in the manner specified
in this section. The steps taking place at the remote station and over the communications line leading to
each of the three primary MOP boot functions are presented in the following sections.
4.7.1
Steps Leading to a Remote Load Detect Boot
The steps taking place at the DMV11 remote station and its host CPU in response to an enter MOP
mode message from the control station are:
1.

The DMVI11 NPRs a tight-loop routine into main memory.

The DMV11 transfers control to the routine through the power fail /restart vector. This routine inactivates the CPU to prevent any intervention during the NPR process.

The DMVI11 then sends a primary MOP request program message to the control station. The
control station responds in turn with a primary MOP memory load with transfer address message containing the boot or related program to be loaded into main memory at the remote
station.

The DMVI11 NPRs that program into main memory, then starts executing the program.

At this point the remote station is operating in the manner intended by the down-line loaded
program.

The steps occurring over the communications line during a remote load detect boot are:

The control station sends an enter MOP mode message to a remote station.

The remote station recognizes the address and password in the message, then inactivates its
host CPU.

The remote station then responds with a primary MOP request program message.

The control station responds to this message with a primary MOP memory load with transfer
address message containing the boot or related program to be loaded into the host CPU at the
remote station.

4.7.2

Steps Leading to a Power-On Boot

When power is restored after a shutdown at a remote station, the DMV11 performs the same steps used
during a remote load detect boot. However, the first two steps performed over the communications line
are omitted, and the tributary station responds to the first poll from the control station with an MOP
request program message. The same sequence used in the remote load detect boot procedure is then
followed.

4-21

4.7.3 Steps Leading to an Invoke Primary MOP Boot
This boot operation is initiated when a user at a remote station sets the boot and master clear bits in the
DMV11 initialization register (see Section 3.3.1). The steps taken by the DMV11 are the same as with
a power-on boot.

' 4.7.4 DMV11 Switch Settings for the Boot Functions
At remote stations, in networks supporting the primary MOP boot functions, the switches must be configured in a specific way in order to properly perform the boot functions (see Section 2.5 and Table 26).
NOTE

The switch setting procedures described below apply
only to tributary stations in a multipoint network
and one node in a point-to-point network.

The unit number (zero or one) of each DMV11 must be appropriately set. This number allows the boot
program, once it is loaded into the host CPU, to identify the specific DMV11 (within the host’s floating
address space) performing the boot.
|
NOTE
When primary MOP booting is supported in a network, the operating mode of each tributary station
eligible for booting must be set in the switches rather
than through the mode definition command.

The operating mode of a DMV
11 is specified by setting the mode enable switch to one (OFF) (switch
number 1 of the boot enable switch pack), and setting switches numbered 6, 7, and 8 to the required
operating mode. The settings for these switches are listed in Table 4-5.

4.7.4.1 Switch Settings for the Power-On Boot Function — To enable the power-on boot function at a
remote station, switch number 4 of the boot enable switch pack (power-on boot) must be set to one
(OFF). In addition, the tributary address of this station must be set in the DDCMP address switch
pack.

4.7.4.2 Switch Settings for the Invoke Primary MOP Boot Function - The DMV11 switch settings for
the invoke primary MOP boot function are the same as those for the power-on boot function. However,
the setting of the power-on boot switch has no affect on the invoke primary MOP boot.
An additional feature of the invoke primary MOP boot and remote load detect is that it may allow the
tributary address of the remote station to be software assigned instead of switch assigned. This feature 1s
only valid for remote stations that are multipoint tributaries. To use this feature, the following conditions
must exist.

The tributary address/password in the DDCMP address switch pack must be zero.

The user program at the remote station must have established the tributary using the control
command (establish tributary). If the remote station is using the multiple address tributary
option, the tributary address used for booting must be the first one established.
NOTE

Invoke primary MOP boot with the software-assigned tributary address does not work if the poweron boot switch is enabled.

4-22

Table 4-§

Mode
Switches

Line
Characteristics

Mode Switch Settings

Network
Configuration

DMC11 Line
Compatibility

ON ON ON

Half-duplex

Point-to-point

Yes

OFF ON

Full-duplex

Point-to-point

Yes

OFF ON

Half-duplex

Point-to-point

OFF OFF ON

Full-duplex

Point-to-point

Half-duplex

OFF

Multipoint control
station

OFF ON

OFF

Full-duplex

N/A

Multipoint control

N/A

station

OFF OFF

Half-duplex

Multipoint tributary

N/A

station

OFF OFF OFF

Full-duplex

Multipoint tributary

N/A

station

4.7.4.3 Switch Settings for the Remote Load Detect Boot Function — To enable the remote load detect
boot function at a remote tributary station, switch number 5 of the boot enable switch pack (enable
remote load detect) must be set to one (OFF). For the remote load detect boot function, the switchspecified tributary address also serves as the password which is contained in the enter MOP mode message.

When using boot functions
in point-to-point networks, the tributary address/password switches can, for
security purposes, be set to a unique value since the address of a point-to-point node is always known to

be one.

4.8
MAINTENANCE REGISTER EMULATION
|
|
The DMV11 is placed into maintenance mode when the user program sets bits 0 and 6 at the same time
in BSEL1. When this happens, the microcode enters a maintenance loop and sets MNT RDY (bit 7 of
BSEL?2) to indicate that the microcode is ready to receive a command as defined by bits zero through
three of BSEL2 (see Figure 4-3). The functions of these commands are described in Table 4-6.

NOTE
The microdiagnostics must complete tests 1-12 as a
minimum before allowing entry into the maintenance
loop.

In the maintenance mode, the functions of the CSRs are redefined as follows:
e

BSELDO, bits zero and four, eénable the respective microprocessor LSI bus interrupts as defined
by bits one and two if an internal 6502 interrupt occurs. See Figure 4-3.

4-23

BSEL?2, bits zero through three, define the maintenance loop command function. Bits four and
five are used for interrupting the CPU on command complete. These interrupts are enabled by
BSELO. Bit seven is set by the microprocessor when the maintenance loop is ready to receive

another command function in bits zero through three (Table 4-6).

SEL4 contains a DMV11 memory location for function codes one through five (Table 4-6).
SEL6 contains data written or read for functlons one, two, and six. It also contains a 16-bit

address for functions three and four.

SEL10 contains the upper address bits for functions three and four. Only the low byte of this
|

CSR is used.

NOTE

BSEL10 and 11 are only used in 22-bit mode.
BSEL12 through 17 are not shown because they are
never used by the user/DMV11-command structure.

REQ

NON-MASKABLE INTERRUPT

RDY

DMV11 MEMORY LOCATION (HIGH BYTE)
FOR FUNCTlONS 1-5

g
MNT

FLAG REGISTER FROM PIA_

BSELS

BSEL7

| uP

INTA | INTB | o~ |BSELO

“A | B

INT | INT

BSEL2

FEJNCT'O.N CODE

SEL2

DMV11 MEMORY LOCATION (LOW BYTE)
FOR FUNCTIONS -8

BSEL4

' SEL4

2?5&6

DATA READ OR WRITTEN FOR FUNCTIONS 1, 2 & 6 or 16 BIT ADDRESS FOR FUNCTIONS 3 & 4
'

BSEL11

15
* M

NOT USED

'
9

" UPPER ADDRESS BITS |

SEL10

UNUSED

OCCURRED

MK-2517

Figure 4-3

DMV11 Maintenance Loop Command Format

4-24

. //az-.-,\\

BSEL3

RUN| CLR

MNT

BSEL

MTR

7
,

Table 4-6

Octal Code
Bits 0-3

Maintenance Command Functions BSEL2 Bits 0-3

Function

Reserved to avoid unpredictable results.

Read DMV11 memory location specified by SEL4 (16-bit address specifying a
byte). SEL6 contains the data read from this location.

Write DMV11 memory location specified by SEL4. SEL6 contains the data
written to this location.

Read 256 bytes of DMV11 memory. SEL4 points to the starting DMV11 memory address from which the information is read. The lower eight bits of this address are ignored. SEL6 and BSELS8 point to the starting LSI-11 bus address
where the information is stored.

Write 256 bytes of DMV11 memory. SEL4 points to the starting DMVII memory address to which the information is written. The lower eight bits of this address are ignored. SEL6 and BSELS point to the starting LSI-11 bus address
o,

from which the information is read.

Set the 6502 microprocessor’s program counter to the value contained in SEL4.
This is used to start the microprocessor executing code at the DMV 11 memory
location specified by SEL4.

Set internal loop and null clock for functional d1agnostlcs Null clock is initialized for 56K b/s.

Set maintenance interrupt flags and clear interrupt disable in processor status.

4-25

CHAPTER 5

ASPECTS OF DMV11
MICROCODE OPERATION

5.1

INTRODUCTION

The functionality of the DMV11 results from the microprocessor and its associated microprogram or
microcode. This chapter discusses the microcode as it relates to:

5.2

The polling algorithm,

Error recording, and

The internal data base.

DMVI11 POLLING ALGORITHM

In a polling operation the tributaries are in effect asked one by one whether they have anything to

transmit. To accomplish this, the control station sends a polling message with a unique tributary address down the line. The station which recognizes the address responds with data messages or a positive
response.

With DMV11s, polling is based on a priority scheme which 1s derived automatically and applied dynamically by the microcode. To control polling and data message transmission, the DMV11 uses the
following information:

The tributary’s recent poll history,

The tributary’s user-defined parameters,

The tributary’s protocol state.

In regard to protocol state, the multipoint network control station polls all established tributaries that
are not in the DDCMP halt state. The protocol state of every established tributary is maintained in the
associated TSS by the control station. When a tributary is eligible for polling, all outstanding transmit
messages for that tributary are sent as the poll, up to the limit imposed by the maximum transmitted
message count. If no transmit messages are available for a tributary eligible for polling, the DMV11
automatically transmits the appropriate DDCMP control message.

The DMV11 polling algorithm determines which tributary is to be polled next, based on each tributary’s polling urgency level. The DMV11 polling algorithm employs the user-defined TSS and GSS polling parameters as the basis for categorizing tributaries into polling levels. The polling algorithm also
determines the rate at which polling urgency is increased within each polling level. A tributary’s polling
level is based on its recent response history. This classification mechanism, combined with periodic incrementing of polling urgency, results in the most active tributaries being polled most often.

5-1

5.2.1
Calculating Polling Urgency
The polling urgency (priority) of each tributary is periodically calculated when a global timer expires.
This periodic calculation enables the algorithm to enforce minimum poll intervals for each tributary,
and to account for competition between tributaries. The minimum poll interval prevents unneeded polls
from:
e
e

Delaying other tributaries,
Interfering with output traffic, and

Causing unnecessary processor overhead.

The polling urgency of a tributary is calculated as a linear function of time elapsed since the last poll.
The calculationis truncated when the maximum value of 255 is reached. The three parameters in this
calculation are:

1.
2.
3.

Q - the initial value of the polling urgency (U);
R —the rate at which Q is to be increased;
DELTA T - the polling algorithm global update interval.

Figure 5-1 shows the relationship between these three parameters. The appropriate choice of Q and R
can give a variety of behaviors. For this reason, the choice of these values must be based on the desired
performance One method of choosing Q and R is to define the minimum poll time and the time to
reach maximum poll urgency, and to use these valuesin the following equations.
Minimum poll time = 128-Q (DELTA T)
R

Time to reach maximum poll urgency = 255-Q (DELTA T)
R

DELTA T is the user-defined period of the global timer and its value depends on the line speed. It must
be smaller than the smallest nonzero minimum poll interval, but no smaller than 200 ms. The poll priority is calculated for each tributary and stored in a single byte of the TSS. With every DELTA T, the
polling urgency byte is updated. The following interpretation is placed on its value. These values are
represented as base lines on the graph of Figure 5-1. Figure 5-2 shows the relationship of the polling
urgency to different values of Q and R.
0- 127

Do not poll the tributary. The minimum poll interval has not expired.

128

Minimum poll interval has expired. The tributary is eligible for polling.

129 — 254

Minimum poll interval is exceeded. The tributary is eligible for polling. The
higher values 1ndlcate increasing priority in the event of competition between
tributaries.

255

Maximum poll urgency is reached. Competition between tributaries at this priority is round-robin.

This method of determining values for Q and R is applicable when static behavior is desired. For many
applications, however, dynamic behavior can improve performance by polling active tributaries at a
faster rate and with a higher priority than inactive tributaries.

During each DELTA T time period, the control station polling algorithm updates the urgency of each
operational tributary by adding the value of R for the approprlate polling state (excluding dead) to the
urgency value of each tributary. This updating sequence is performed on the TSS data basein the order

5-2

.
P

in which tributaries were originally established at the control station. When the polling algorithm determines that the next poll is to be sent, it selects the tributary to be polled by scanning the TSS data base
(in the original order of tributary establishment), starting at the TSS following the last tributary polled.
In this process, the tributary having the highest value of U from active, inactive, and unresponsive
tributaries is selected as the next tributary to be polled.
TIME TO
MAXIMUM URGENCY

255

F‘—————_————————— ————————————————

ELIGIBLE FOR
POLLING

=)
;

MINIMUM

POLLING INTERVAL

127

ee
——

NOT POLLED

/,/

ry171917v

—>l l‘—At

1717

¢y

¥y

vyvyovy

yvrrve

At = 200ms

MK-2643

Figure 5-1

Interrelationship Between Polling Parameters Q, R, and DELTA T

If an urgency of 255 is detected during the process of scanning the TSS data base for the tributary

having the highest value of U, the scan process is halted and that tributary is immediately selected for
polling. Once the selected tributary is polled, its urgency reverts to the assigned value of Q for its polling level.

Dead tributaries are polled at a rate determined by the user-defined parameter DEAD T. One dead

tributary is polled at each expiration of the DEAD T timer, and the scan of dead tributaries is resumed
from the last dead tributary polled.

5-3

255

|
|

I
|

|
'

;

]

=
>

LZJ

127
|

I
l

|
|
|

200ms

—

3.2

'
|
|

4.0

6.375
DELTA

Figure 5-2

0 e
~>|

Vio

V.,

8.0
T

9.55

12.0

‘I

16.0

200ms

MK-2647

Relationship Between Polling Parameters Q, R, and the Minimum Polling Interval

The dynamic polling algorithm uses Q and R values based on dynamically modified states. There are
four of these states:

Active — The polling algorithm maintains a tributary as active when it responds to polls with
data messages.

5-4

parameter DEAD T (dead timer).

///

Unresponsive — A tributary currently active or inactive is changed to the unresponsive state
when it fails to respond in any way to a consecutive number of polls (each poll results in a
selection timeout). The count of consecutive polls without responses is designated by the
user-defined parameter TO-UNRESP (number of timeouts to go unresponsive).
Dead — A currently unresponsive tributary which continues to be unresponsive to consecutive
polls is changed to dead. This occurs when the number of selection interval timeouts designated by the user-defined parameter TO-DEAD (number of timeouts to go dead) is exceeded. Unlike tributaries in the other polling states, dead tributaries are always polled on a
round-robin basis with the period between polls being determined by the user-defined global

to a
Inactive — The polling state of an active tributary is changed to inactive when it responds
nonconsecutive number of polls with nondata DDCMP messages. The count of consecutive
data messages received from a tributary in the active state is designated by the user-defined
parameter NDM-INACT (number of no-data messages required to go inactive).

When specifying the parameters controlling polling levels, the user has the option of accepting the
defaults (see Table 4-2 and 4-3), or selecting specific values in place of these defaults. The user pro-

gram can set the polling state of a tributary to any state at any time by issuing a latch polling state
control command. The polling state imposed by a control command remains in effect, irrespective of

tributary performance, until polling control is handed back to the polling algorithm by the user program. This is done by issuing an unlatch polling state control command.

Figure 5-3 shows the relationship of the the default values of Q and R for the active, inactive, and |
~unresponsive polling states.

255
ACTIVE Q=255,

R=0

ELIGIBLE FOR

POLLING
)

)/
Q~/

4
=)

>
8]
Z
Ll

&
S

128—4

—

So
—

—
-

O
a

NOT POLLED

200ms

1.2sec

2.60sec

]

DELTA T =200ms
MK-2642

Figure 5-3

Relationship Between the Default Values for Q and R for the Three

Polling Activity Levels

Each tributary has Q and R values defined by the user for the active, inactive, and unresponsive polling
states. This allows dynamic modification of the behavior of the polling algorithm. The basic mechanics
of the polling algorithm are:

If a tributary always responds to a poll with data, it remains in the active state. The polling
urgency in this case is calculated using the Q and R values specified for the active state.

If a tributary responds to a user-defined number of consecutive polls with no data messages
(ACKs only), polling is changed to inactive. The polling urgency is then calculated based on
the Q and R values defined for the inactive state.

If a tributary in either the active or inactive states fails to respond (times out) to a predetermined number of consecutive polls, the polling state is changed to unresponsive. The Q
~and R values defined for the unresponsive state are used to calculate the polling urgency.

If a tributary in the unresponsive state fails to respond to a predetermined number of consecutive polls, the polling state is changed to dead. The user is notified of this transition by a
control response. Polling dead tributaries is very time-consuming because it usually requires
a timeout. Therefore, dead tributaries are not polled on a priority basis. Instead, a global poll
interval is defined for dead tributaries. Each time this timer expires, a single dead tributary
is polled. If at any time a dead tributary responds to a poll with a data message or ACK, its
state is changed to active.

NOTE

A tributary (not in the active polling state) is automatically returned to the active state when it responds to a poll with a valid data message. It also
becomes active when the user program allocates a
transmit buffer to it.

Figure 5-4 is a state diagram describing the transitions between polling states. The actual transitions are
dependent on the particular polling parameters.

The user may control sending of all polls by defining a poll delay interval that must expire before a poll
can be sent.

The program-selectable parameters which pertain to polling are included in Table 4-2. These parameters are set by the user with a-write TSS command.

5.2.2

Criteria for Determining Polling Parameters

Although there are no absolute rules for determining polling parameters, there are general guidelines
for deriving them. These guidelines are presented in sections 5.2.2.1 through 5.2.2.4.

5.2.2.1 Determining a Value for DELTA T - For most multipoint network applications, the default
value of 200 ms for DELTA T is adequate. The default value of 200 ms is the smallest permissible
value for DELTA T and represents the actual time required for the microcode to update the urgencies
of 12 tributaries. However, in specific cases a higher value of DELTA T might be recommended. An
example of this is a network formed by low traffic devices.

5-6

(

NOTE

The minimum polling interval defines the time required for a tributary to reach the urgency threshold
value of 128. This is the minimum time required to
be eligible for polling. The maximum polling interval
cannot be determined. This is because it is a function
of line speed, message traffic, the number of tributaries in a network, and the polling states of those
tributaries. These variables make it impossible to
predict the time at which any tributary in a network
is polled.

ACTIVE
(NDM — INACT)

(TO — UNRSP)

UNRESPONSIVE

]

(TO — DEAD)

MK-19586

Figure 5-4

State Diagram of Polling State Transitions

5.2.2.2 Determining Values for Q and R - For a given value of DELTA T, the minimum polling interval is a function of the user-defined parameters Q and R. For example, if a minimum polling interval of

3.2 seconds is desired for a tributary (assuming DELTA T = 200 ms), the parameters Q = 0,and R =

8 satisfy this requirement. With these values of Q and R, the time to reach maximum polling urgency is
5-7

6.375 seconds (see Figure 5-2). Notice that if Q = 64 and R = 4, the minimum polling interval remains at 3.2 seconds but the maximum polling urgency increases to 9.55 seconds.
NOTE
Reaching maximum polling urgency represents maximum eligibility for polling, but does not guarantee
that a tributary will be polled.

Figure 5-3 graphs the relationship between the default values of Q and R for each of the three polling

states. When all tributaries in a network have the default value for Q and R, and all tributaries are in
the active polling state, the manner of polling is round-robin.

5.2.2.3 Determining a Value for Poll Delay - The user-defined global parameter poll delay imposes a
fixed delay between control station polls. This provides a mechanism for regulating message traffic
without changing the values of Q and R for individual tributaries. During this delay, transmission from
the control station to tributaries is halted for the interval defined by the poll delay timer. This interval
begins when the tributary just polled deselects itself.

The ability to regulate message traffic through a single parameter is valuable in multipoint networks.
This is especially true where DMV11s are configured together with slower character interrupt communication devices such as DUP11s. The value selected for poll delay in these circumstances is a function
of the character handling rates of the non-DMV11 devices.

In remote multipoint networks where the distance between the control station and tributaries varies
significantly, there is a greater chance of transmit and receive errors. This is due to the difference in
communication line settling time in such a network. In such instances, the settling time for the most
distant tributary station should be used for determining a value for poll delay.

For DMV 1-implemented high-speed local networks, this parameter is unnecessary. The default value

(zero) for poll delay is used in these networks.

5.2.2.4 Determining a Value for DEAD T - This global parameter establishes the rate at which dead

tributaries are polled. Dead tributaries are polled on a round-robin basis, with one tributary polled at
each expiration of the dead tributary timer.

Polling dead tributaries can significantly impact network line utilization. The shorter the period of this
timer — the greater the impact. For a given value of DEAD T, the impact decreases as system line
speed increases. When determining a value for this parameter, the primary goal is to minimize the im|

pact on network line utilization.

The value for DEAD T should be based on the period of the selection interval timer for the specific
application. For example, if the period of the dead tributary timer and the selection interval timer are
equal, only dead tributaries are polled. For most system applications, the period of the dead tributary
should be from three to ten times greater than that of the selection interval timer. This of course depends on line speed. The default value for DEAD T is ten seconds. This is about three times the default
value for the selection interval timer.

5.3

ERROR COUNTERS

In multipoint networks many tributaries tie to the same transmission line. Because of this, it is more
difficult to determine which link, if any, is causing errors. To aid in troubleshooting, the DMVII maintains extensive error counters. Every DMV11 in the network (the control station and each tributary)
uses error counters to record errors. This allows user programs at any DMV11 in the network to deter'
mine overall error rates and to detect a malfunctioning link.
5-8

Data link errors are indicated to the DMV11 by DDCMP negative acknowledge messages (NAKS).
Each NAK contains an address field and a reason code that identifies the source and reason for the

NAK. In general, when an error is detected in an incoming message, the station that receives the message sends a NAK to the station that sent the message. By recording NAKs sent and NAKSs received,
each point or tributary in the network is able to compile statistics on the condition of the link established between the two stations. DDCMP error recording has been designed so that even if one of the
stations on the link cannot record errors, the other station may be used to record errors for all communications in both directions on the link.

There are three main categories of error counters used by the DMV11; data link counters, station
counters, and threshold counters. Data link counters and threshold counters are maintained for each
tributary/control station pair on a physical link. These counters are located in the tributary status slots
of the data memory (Figure 5-5). Station counters are maintained for the physical link as a whole, and
are located in the global status slots of the data memory (Figure 5-6). Unless otherwise stated, all
counters increment to a maximum value and hold that value until cleared.

5.3.1
Data Link Error Counters
|
Data link counters are of two types; cumulatlve and background. The cumulative counters are 8-bit
registers which latch at 255. The background counters are 16-bit registers which latch at 65535. The
cumulative data link counters record and total all occurrences of an error and group them into the following categories.

Data errors outbound,
Data errors inbound,
Local reply timeouts,
Remote reply timeouts,
Local buffer errors,
Remote buffer errors,
Selection timeouts.
Background data link counters are used to provide a statistical base for the cumulative error counters
and therefore record:
e

The number of data messages transmitted,

e
e

The number of data messages received, and
The number of selection intervals.

A point-to-point station maintains a single set of data link counters. Multipoint stations (control and
tributary) maintain a separate set of data link counters for each established tributary. Data link
counters are cleared by:
e
e
e

A master clear of the DMVI11,
A control command to estabhsh the tributary, or
A user-issued control command to read and clear the TSS error counters

5.3.1.1 Data Errors Outbound - This 8-bit group counter records NAKs received for data errors occurring on the communications channel outbound from this station. There are three types of outbound
errors for which this counter records NAKs received; header blockcheck (OHBCC), data field blockcheck (ODBCC), and reply response (OREP). Three separate flag bits indicate which type of outbound
error is being counted.

OHBCC (outbound header blockcheck) is set when a NAK with a reason code of one is received for a header block-check error for either data or control messages.

5-9

ODBCC (outbound data field blockcheck) is set when a NAK with a reason code of two is
received for a data field block-check error.

OREP (outbound reply response) is set when a NAK with a reason code of three is received
for a reply message response.

TRIBUTARY STATUS SLOT (TSS)
ADDRESS (OCTAL)

RESERVED
RECEIVE THRESHOLD ERRORS

TRANSMIT THRESHOLD ERRORS
SELECTION THRESHOLD ERRORS

7
—

DATA MESSAGES TRANSMITTED

—

DATA MESSAGES RECEIVED

—

SELECTION INTERVALS

—_—

DATA ERRORS OUTBOUND

RESERVED

I OREP | ODBCC l OHBCC

DATA ERRORS INBOUND
RESERVED

I IREP | IDBCCI IHBCC

LOCAL BUFFER ERRORS

'RESERVED
15

LBTS I LBTU

REMOTE BUFFER ERRORS

16
17

RESERVED

I RBTS | RBTU

SELECTION TIMEOUTS

RESERVED

| IRTS I NRTS

LOCAL REPLY TIMEOUTS
REMOTE REPLY TIMEOUTS

MK-1960

Figure 5-5

Data Link and Threshold Error Counters

- 5-10

GLOBAL STATUS SLOT (GSS)
ADDRESS (OCTAL)

REMOTE STATION ERRORS

l RSTR I RSEL IRMHFE ROVRN
16

LOCAL STATION ERRORS

I LOVR ILUNDR LMHFE | LOVRN
17

GLOBAL HEADER BLOCK CHECK ERRORS
MAINT. DATA BLOCK CHECK ERRORS

MK-1959

Figure 5-6

Station Error Counters

5.3.1.2 Data Errors Inbound — This 8-bit group counter records occurrences which normally result
from data errors on the communications channel inbound to this station. Three separate bits indicate
specific error types associated with this counter.

IHBCC (inbound header blockcheck) is set when messages having header-block check errors
are received. When this error occurs, point-to-point stations and multipoint control stations
send a NAK with a reason code of one. A multipoint control station records this error for the
selected tributary regardless of the address field in the received message. A multipoint tributary records this error only if the address field matches its station address.

e
e

IDBCC (inbound data field blockcheck) is set when NAKs with a reason code of two are to

be sent for data field block-check errors.

[REP (inbound reply response) is set when NAKs with a reason code of three are to be sent

for a reply response.

5.3.1.3

Local Reply Timeouts — This 8-bit counter records occurrences which result from:

The loss of communications between two stations while the one recording this error has data
to transmit, or

The choice of an inappropriate value for the reply timer.

‘Specifically, this error counter records the sending of a REP message.

5.3.1.4
e

Remote Reply Timeouts — This 8-bit counter records occurrences which result from:
The loss of communications between two stations while the remote station has data to transmit, or

The choice of an inappropriate value for the remote station reply timer.

Specifically, this counter records ACKs sent in response to a REP. The remote station sent a REP
because it received no acknowledgement for messages it previously sent. The local station received
those messages, but the remote station never received the acknowledgement.

5-11

5.3.1.5 Local Buffer Errors — This 8-bit counter records the fact that the user program at the station
recording the error failed to properly allocate receive buffers to data messages from the remote station.
Two separate bits indicate the specific errors associated with this counter.

LBTU (local buffer temporarily unavailable) is set when a buffer is temporarily unavailable.
This condition indicates that a NAK with a reason code of eight is to be sent.

LBTS (local buffer too small) is set when a local buffer is too small for the incoming message. This condition indicates that a NAK with a reason code of 16 is to be sent.

3.3.1.6 Remote Buffer Errors — This 8-bit counter records the fact that the user program at the remote
station failed to properly allocate receive buffers to data messages from the station recording the error.
Two separate bits indicate the specific errors assomated with this counter.
e

RBTU (remote receive buffer temporarily unavailable) is set when a NAK with a reason
code of eight is received.

RBTS (remote receive buffer too small) is set when a NAK with a reason code of 16 is received.

5.3.1.7
e
e
e

Selection Timeouts — This 8-bit counter records the occurrences which result from:
Loss of communications with a remote station,
Data errors on the communications channel to or from the remote station, and
The choice of an inappropriate value for this station’s select timer.

This counter is used only by half-duplex point-to-point or multipoint control stations. Two separate bits
indicate the specific errors associated with this counter.
e

NRTS (no reply to select) is used to record selection intervals in which no transmission is

received from the tributary, and no attempt to transmit is detected. Specifically, it records
the expiration of the select timer without the receipt of a valid control message or header, or
the detection of an attempted transmission.

[RTS (incomplete reply to select) is used to record selection intervals which were not properly terminated. Specifically, it records the expiration of the select timer preceded by receipt
of a valid control message, receipt of a valid header, or detection of an attempted transmission. An attempted transmission is indicated by:
—
—
- —

The presence of a carrier signal,
The receipt of a DDCMP synchronization sequence, and
The receipt of an SOH, ENQ, or DLE.

included in this count.

5-12

m_\

///

5.3.1.9 Data Messages Received — This 16-bit counter records messages received by this station, and
latches at a count of 65535. It can be used as a statistical base when evaluating data errors inbound,
remote reply timeouts, and local buffer errors. Messages received out of sequence or in error are not

5.3.1.8 Data Messages Transmitted — This 16-bit counter records messages transmitted by this station,
and latches at a count of 65535. It can be used as a statistical base when evaluating data errors outbound, local reply timeouts, and remote buffer errors. Messages sent as a result of retransmission are
" not included in this count.

5.3.1.10 Selection Intervals — This 16-bit counter records the number of times this station selects the
other station. It also latches at a count of 65535. Specifically, it records the number of messages transmitted with the select flag on. It is only used by half-duplex point-to-point and multipoint control stations. It can be used as a statistical base when evaluating the number of selection timeouts.
5.3.2

Station Error Counters
|
Station counters are 8-bit counters which latch at 255 and record unusual occurrences. These occurrences may be the result of:

A hardware or software fault at this station,

A hardware or software fault at a remote station, or

A data error on the communications channels undetected by the header block-check field.

A single set of these counters is used for all tributaries on a multipoint link.

There are four types of station counters:
Remote station errors,
Local station errors,
Global header block-check errors, and
Maintenance data field block-check errors.

Station counters are cleared by:
e
e

A master clear of the DMV11, or
A user-issued control command to read and clear the GSS error counters.

5.3.2.1 Remote Station Errors — This 8-bit counter records occurrences caused by a fault in a remote
station or by an undetected data error on the channel inbound to this station. Four separate bits indicate
the specific errors associated with this error counter.
e

ROVRN (remote receive overrun) is set when a NAK with a reason code of nine is received
for a receive overrun.

RMHFE (remote message header format errors) is set when a message is received which has
a header format error. This condition indicates that a NAK with a reason code of 17 is to be
sent.

RSEL (remote selection address error) is set when a multipoint control station receives a
message containing an address field which does not match the address of the currently selected tributary. RSEL is a flag used only by multipoint control stations.

RSTR (remote streaming tributaries) is set by either one of two events: 1) an implementation-dependent maximum transmission interval is exceeded without releasing the channel
(babbling tributary), or 2) the channel is not released following the end of a selection interval
(streaming tributary).
~

5.3.2.2 Local Station Errors — This 8-bit counter records occurrences caused by a fault in a local station or by an undetected data error on the channel outbound from this station. Four separate bits indicate the specific errors associated with this error counter.
e

LOVRN (local receive overrun, NAK sent) is set for local station receive overruns. This condition indicates a NAK with a reason code of nine is to be sent.

5-13

LOVR (local receive overrun, NAK not sent) is set by a receive overrun when a NAK is not
sent. For a multipoint tributary, this happens if an overrun occurs while receiving a header.
For other stations, this occurs when the station is not in the DDCMP run state.

LUNDR (local transmit underruns) is set when a transmit underrun occurs.

LMHFE (local message header format error) is set when a NAK with a reason code of 17 is

received to indicate a message with a header format error was sent by this station.

5.3.2.3 Global Header Block-Check Errors — This 8-bit counter records the occurrence of header
block-check errors that are not recorded on a per tributary basis. Specifically, it counts header blockcheck errors for maintenance messages and for messages to tributaries where the address field does not
match the station address.

§.3.2.4

Maintenance Data Field Block-Check Errors — This 8-bit counter records the occurrence of

data field block-check errors for maintenance messages.
Threshold Error Counters

5.3.3

Threshold error counters are used to determine if a persistent fault exists. A persistent fault is one
which occurs seven consecutive times. Whenever a threshold counter reaches its maximum value (7),
the user program is notified by a control response.

In the DDCMP run state, threshold counters are cleared when the user is notified. In this way the user
is continually informed of a persistent fault. In the DDCMP ISTRT and ASTRT states, threshold
counters are not cleared when the user is notified. In this way the user is not continually informed of an
inoperative remote station.

A point-to-point station maintains a single set of threshold counters. A multipoint control station maintains a separate set for each tributary. A multipoint tributary maintains a single set unless it supports
multiple tributary addresses in which case it maintains a single set for each established tributary address.

5.3.3.1

Transmit Threshold Errors — This 3-bit counter is incremented (if less than seven) in the fol-

\‘x‘

There are three types of threshold error counters: transmit, receive, and selection.

;

lowing instances.

The DMVI1 is in the ISTRT state when a STRT message is sent,

The DMVI1I is in the ASTRT state when a STACK message is sent, or

3. The DMV11 is in the run state and a NAK with a reason code other than three (REP response) is received, or when sending a REP message.

While in the run state one of the following occurs:

—

A transmit threshold error is reported,

—

A NAK, ACK, or data message is received acknowledging a new message, or

—

A NAK, ACK, or data message is received when no messages are outstanding.

5-14

PalianN

Upon entering the ISTRT, ASTRT, or run states.

)

The transmit threshold error counter is cleared:

Reason Code

Description

—\D
O0 W NI =

5.3.3.2 Receive Threshold Errors — This 3-bit counter is incremented (if less than seven) when a NAK
with one of the following reason codesis sent.

‘Header block-check error.
Data field block-check error.
REP response.

Buffer temporarily unavailable.
Receive overrun.

Message header format error.

This counter is cleared when:
e

Entering the ISTRT, ASTRT, or run states,

A control message with a correct header blockcheck is received without a header format error,

A data message with correct header and data field blockchecksis received without a header
format error, or

In the run state, a receive threshold error is reported.

'5.3.3.3

Selection Threshold Errors — This 3-bit counter is only used by mu.ltipoint control stations and

curs.

)

‘

half-duplex point-to-point stations. It is incremented (if less than seven) when a selection timeout oc-

It is cleared upon receipt of a message with the select bit set, or while in the run state and a selection
threshold error is reported.
5.4

DMV11 MICROCODE INTERNAL DATA BASE OVERVIEW

Functionally, the DMV11 internal data base provides the mechanism for managing:

The assignment and completion of transmit and receive buffers,

The queuing of DMV11 responses,

The assignment of TSS structures to established tributaries for the storage and maintenance
of tributary and global status information.

A map of this data base is shown in Figure 5-7. The data base is implemented by three basic structures:

e
e
e

Linked lists,
Slot mapping table,
TSS and GSS structures.

Each of these are described below in terms of organization and function.
S.4.1

Linked Lists

r—

A linked list is an open-ended data list made up of fixed-length blocks linked by pointers. Each of these
blocks (link blocks), contain seven bytes of data and a one byte pointer to the next link block in the list.
The pointer in the last block in the list is a terminator value. Figures 5-8 and 5-9 illustrate the standard
format for DMV11 linked-list structures.
|
|

5-15

HEXADECIMAL

0000

SCRATCH PADS

16 BYTES

Q-BUS CSRs

8 BYTES

SCRATCH PADS

3 BYTES

OUT NPR ADDRESS

SCRATCH PAD

1 BYTE

IN NPR ADDRESS

3 BYTES

SCRATCH PAD

BYTE

GLOBAL STATUS SLOT

1FF

32 BYTES

64 BYTES
,

SLOT MAPPING TABLE (SMT)

256 BYTES

MICROPROCESSOR STACK

64 BYTES

BUFFER AND OUTPUT QUEUE

c00

98 ENTRIES

8 BYTES/ENTRY

TRIBUTARY STATUS SLOTS

12 ENTRIES

64 BYTES/ENTRY

800
MK-2495

Figure 5-7

Data Memory Map

A DMVI11 linked list is made up of five kinds of linked lists.
1.

The free linked list — A list of empty link blocks used by the microcode to form the remaining
kinds of linked lists.

The response linked list — A queue of responses for posting to the user program.

The common buffer pool linked list — A list of the accessing information for each receive
buffer assigned to the common pool. There is one link block for each assigned buffer.
Receive buffer linked list — A list of receive buffer accessing information. One of these is
maintained by the microcode for each established tributary having private receive buffers

assigned. There is one link block for each buffer.

Transmit buffer linked list — A list of transmit buffer accessing information. One of these is

maintained by the microcode for each established tributary having transmit buffers assigned.

There is one linked list for each buffer.

5.4.1.1 The Free Linked List — The free linked list from which all other linked lists draw link blocks, is
maintained in the lower section of data memory called the buffer and output queue (BOQ) (Figure 57). These 832 bytes translate into a total of 104 link blocks available for use by the operational linked
lists. In this way, the free linked list functions as a finite resource for the operational linked lists.
5-16

START OF LIST
POINTER

)

LINK BLOCK
POINTER A

DATA

LINK BLOCK
POINTER B

DATA

LINK BLOCK
POINTER C

DATA

o E
oF
oN

3778

1——-{

TERMINATOR

DATA

MK-1961

Figure 5-8 DMVI11 Linked List Structure Format
As previously stated, a linked list is equipped with two list pointers; one that points to the start of the
list and one that points to the end of the list. When a link block is removed from the free linked list, the start of the list pointer is changed to point to the next available link block in the free linked list. When a
link block is completed by one of the operational linked lists, it is added to the end of the free linked list
and its internal pointer is set to the terminator value of 377 octal. In addition, the internal pointer in the .
next to last link block is changed from 377 octal to the address of the link block just added. The-startand end-of-list pointers for the free linked list are maintained
in the station GSS.
|

5-17

Link blocks are removed from the free linked list and added to the receive, transmit, or common pool
buffer linked lists when the user program issues control or buffer address/character count commands
for that purpose. Similarly, link blocks are removed from the free linked list and added to the response
linked list when the DMV 11 microcode posts a response
to the user program. If the last link block is
removed from the free linked list, the start of the list pointer is set to the terminator value of 377 octal
to indicate there are no more link blocks available. In this event, the next request for a link block generates the fatal error QUEUE OVERFLOW. For this reason, the buffer allocation strategy for a user
program must be designed to assure an adequate number of link blocks.

LINK POINTER

POINTER TO THE NEXT LINK BLOCK

MESSAGE NUMBER

DDCMP MESSAGE NUMBER

BSEL 3

TRIBUTARY ADDRESS

BSEL 4

BUS ADDRESS

BSEL 5

BUS ADDRESS

BSEL 6

'CHARACTER COUNT LOW

BSEL 7

CHARACTER CNT HIGH, BA 16, BA 17

BSEL 2

'TYPE‘ CODE AND BA 1‘8-21

Standard Link Block

Figure 5-9

MK-2497

5.4.1.2

The Response Linked List — This linked list functions as a queue of buffer disposition, control,

and information responses to be posted to the user program. The format of the link block for each of
these three responses is shown in Figure 5-8. When preparing a link to convey a control or information
response, the microcode clears all unused bit positions in the link block to zero. However, link blocks
restored to the free linked list remain unchanged.

The start-of’-list'and end-of-list pointers for the responsé linked list are maintained in the station GSS.
5.4.1.3

Buffer Lmked Lists — A buffer linked listis prov1ded for each type of message buffer allocated

by a user program. These are:

e
e
e

Common pool receive buffers,
Private receive buffers, and
Transmit buffers.

Each link block in a buffer linked list provides the location and size of a buffer in main memory.

The Common Buffer Pool Linked List — This linked list provides a queue of receive buffers available to
all established tributaries according to the quota assigned to each tributary.

Common pool buffers are assigned through the buffer address/character count command, and enabled
with tributary quota assignments through the control command (see Section 3.3. 3) The start-of-list and
end-of-list pointers for this linked list are maintainedin the station GSS.

Receive Buffer Linked List — This linked list serves as a queue of private receive buffers. One list is
maintained for each tributary established at a multipoint station. For point-to-point stations, one listis
maintained at each station. The start- and end-of-list pointers for each receive buffer linked list are
maintainedin the assomated tributary’s (or station’s) TSS

5-18

Transmit Buffer Linked List — This list functions as a queue of transmit buffers. One list is maintained

for each tributary established at a multipoint station. For point-to-point stations, one listis maintained
at each station. The start- and end-of-list pointers for each transmit buffer hnked list are maintainedin

the associated tributary’s (or station’s) TSS.

A unique feature of this link block is the message number field. When a message is transmitted from a

buffer, the header of that message contains the DDCMP message number (in the message number

field). The microcode uses this field to locate the buffer for a message that has been NAKed after
transmission and, therefore, must be retransmitted.
5.4.2

Slot Mapping Table
Under DDCMP, the 8-bit message header address field permits a maximum of 255 unique tributary
addresses in a multipoint network. However, the DMV 11 microcode limits the number of established
tributaries to 12. In order to implement DDCMP, a tributary in a DMV11-based multipoint network
can have a TSS address in the range of 1 to 255. However, only 12 of these tributaries may be established at any one time.

TSS addresses are assigned at both control and tributary stations through the slot mapping table
(SMT). As shown in Figure 5-7, this table occupies 256 locations in DMV11 data memory; one location
for each of the 255 possible tributary addresses, and one location to address the GSS.
The function of the SMT is to map an 8-bit tributary address into one of the 12 available TSS structures. When a tributary is deleted, its TSS and SMT entry is released for reassignment. When 12 tributaries are established and an attempt is made to establish a 13th, a procedural error is posted to the user
program.

5.4.3 TSS and GSS Structures
|
The TSS and GSS structures occupy separate sections of data memory. The GSS is a single 64-byte
section while the TSS structure consists of twelve 64-byte sections.

- 5.4.3.1

The Global Status Slot (GSS) - Functionally, the GSS is used to:

Maintain control and status information specific to the operation of the microcode,

Record event counts and error conditions that are global in nature, and

Store global parameters.

The majonty of the GSSis devoted to microcode control and status information. A detailed map of the
GSSis shownin Figure 5-10.
Access to the GSS is accomplished on word boundaries. A user program can read any GSS location
through the control command. The content of the addressed location is transferred to the user program

through an information response. A user program can read and clear only GSS station error counters.
The four global parameters (locatlons 34 through 37) are written by the user program through the con-

trol command.

nalb
el e

5.4.3.2 Tributary Status Slots (TSS) - A TSS contains four general categorles of tributary information (Figure 5-11):

Protocol and tributary status,
Error and statistical counters,
Message exchange variables, and
Polling parameters.

5-19

Protocol and Tributary Status — This category includes information on the tributary’s protocol state, its
status with relation to the logical communications line, its protocol status, and its polling status. Tributary polling status is maintained only at a multipoint network control station. Although this informa- tion is only pertinent to, and used by the DMV11 microcode, it can be read by a user program.

Error and Statistical Counters — These counters provide the user program with a wide range of error
counts, and a set of statistical counts that permit analysis of the meaning of specific error counts. These
counters can be read and cleared by the user program. The function of each of these counters is described in detail in Section 5.3.
|

Message Exchange Variables — This category includes a range of variables used by the microcode to
control the transmission and reception of message data. This includes the common buffer pool quota
|

assigned by the user program.

A group of timers is also included in the message exchange variables. These timers can be preset to a
specific timeout value by the user program, and directly concern message traffic transferred on the
logical link by the associated tributary. These timers are referred to as:
Transmit delay timer,

Selection interval timer,*

Maximum transmitted message count,
Babbling tributary timer.

The link management functions performed by these timers is detailed in Chapter 4,
Polling Parameters — These parameters are user-defined values that are used by the polling algorithm
to conduct dynamic polling activity in multipoint networks. The functions performed by the DMV11
polling algorithm, and the criteria for determining the values for each parameter, are discussed in detail
|

PTM

in Section 5.2.

*A timeout value for the selection interval timer is maintained in each tributary’s TSS, but the actual timer is maintained in
|
|
|
the GSS.
5-20

- GSSs

GSS

ADDRESS

o |

porrtr

'RPM CNTR

RCVPTR
1

XMTPTR

12|

NASP

BUFPTR
3

4 |

s/OF

E/OF

s/oa

TIMER STATUS |

FLAG REGISTER “D”

CLEAR TO SEND TIMER (LOW)

REMOTE STATION ERRORS

RSTR | RSEL

S/R TIMER (LOW)
7

UNUSED

(HIGH)

s/0C
E/OC

MODEM

MODE

~ E/0Q
5

ACKTIM (LOW
ACKTIM (HIGH)

TSP

(HIGH)

|RMHFE|ROVRN

LOCAL STATION ERRORS
LOVR | LUNDR| LMHFE|LOVRN

(HIGH)

B/CW TIMER (LOW)

GLOBAL HDR BCC ERRORS

MAINT DATA BCC ERRORS
MK-2489

Figure 5-10

Global Status Slot (Sheet 1 of 2)

3-21

GSS

ADDRESS

XHDR

(1)

POLL DELAY TIMER (LOW)
(HIGH)

(2)

(3)

POLL UPDATE POINTER

" DEAD SCAN

(4)
22

(5)

CARRIER LOSS TIMER

USYRT HANG TIMER

(6)
23

NUMBER OF SYNCS

RCVHDR (1)

RESERVED

(2)

(3)

CARRIER WAIT

(4)
25

TIMER COUNTER

(5)

DELTA T

R TIMER (LOW)

DEAD T

(LOW)
(HIGH)

(HIGH)
27

C(Low)

(HIGH)

(6)

D TIMER (LOW)

POLL DELAY

(LOW)
(HIGH)

(HIGH)

MK-2490

Figure 5-10

Global Status Slot (Sheet 2 of 2)

5-22

1SS

TSS

ADDRESS

10 |

TRIB STATUS FLAGS

NAK REASON

RECEIVED
11

SELECTIQN

TRIBUTARY ADDRESS

POLL STATUS FLAGS

INTERVALS

DATA ERRORS OUTBOUND

POLL STATUS FLAGS
3

POLL RATE (Ri)

RESERVED|
13

RESERVED

RESERVED|
14

COMMON POOL QUOTA

RESERVED
15

RESERVED

IREP|

|IDBCC|

IHBCC

LBTS

LBTU -

RBTS!|

RBTU

SELECTION TIMEOUTS

RESERVED |

IRTS| NRTS

SELECTION THRESHOLD ERRORS

OHBCC

REMOTE BUFFER ERRORS

RECEIVE THRESHOLD ERRORS

6 | TRANSMIT THRESHOLD ERRORS

0ODBCC|

LOCAL BUFFER ERRORS

MAX MSG COUNTER

OREP|

DATA ERRORS INBOUND

POLL PRIORITY (Vi)

DATA MESSAGES

DATA

MESSAGES

TRANSMITTED

17 | LOCAL REPLY TIMEOUTS
REMOTE REPLY TIMEOUTS

MK-2722

Figure 5-11

Tributary Status Slot (Sheet 1 of 2)

1SS

TSS

ADDRESS

N HIGHEST MSG NUMBER XMIT'D

PRESET VALUE FOR TRANSMIT

A HIGHEST MSG NUMBER ACK'D
21

DELAY TIMER
31

T NEXT MSG NUMBER TO XMIT

R VALUE FOR ACTIVE STATE

TPTR ADDR OF LNKBK FOR MSG T

X LAST MSG NUMBER XMIT'T

CX (CONTROL X REPLY T/0)

E/OX END OF XMIT BUFFER QUEUE

R HIGHEST MSG NUMBER RCV'D
25

S/OR START OF RCV BUFFER QUEUE

- TRANSMIT

36 |

DELAY

#NDM

-->

#T/0

--->

INACTIVE STATE

UMRSP

#T/0 .-> DEAD STATE
SELECTION INTERVAL
TIMING COUNTER

TIMER
27

VALUE FOR UMRSP

MAXIMUM MESSAGE COUNTER

E/OR END OF RCV BUFFER QUEUE

Q VALUE FOR UMRSP
R

- S/DX START OF XMIT BUF QUEUE

Q VALUE FOR INACTIVE STATE
R VALUE FOR INACTIVE STATE

XPTR ADDR OF LNKBK FOR MSG X

Q VALUE FOR ACTIVE STATE

NO DATA MESSAGE COUNTER

BABBLING TRIBUTARY
TIMING COUNTER

T/0 COUNTER

MK-2721

Figure 5-11

Tributary Status Slot (Sheet 2 of 2)

5-24

APPENDIX A

DDCMP

A.1

DDCMP

The Digital Data Communications Message Protocol (DDCMP) provides a data link control procedure
that ensures a reliable data communication path between communication devices connected by data
links. DDCMP has been designed to operate over full- and half-duplex synchronous and asynchronous
channels in both point-to-point and multipoint modes. It can be used in a variety of applications such as
distributed computer networks, host front-end processors, remote terminal concentrators, and remote
job entry-exit systems.

A.1.1
Controlling Data Transfers
|
The DDCMP message format is shown in Figure A-1. Three control characters are provided in
DDCMP to differentiate between the three possible types of messages:

e
N

e
e

SOH - Data message follows,
ENQ - Control message follows,
DLE - Maintenance message follows.

Note that the use of a fixed-length header and message size declaration obviates the requirement for
extensive message and header delimiter codes.

SYNL

ISYNY

COUNT | FLAG

|RESPONSE | SEQUENCE |ADDRESS|CRC-1

159 14 sits|2 BiTs|s BiTs

g BITS

|8 BITS

DATA

CRC-2

|16 BITS| CHARACTERS
ANY NUMBERUPOFTO8-BIT
|1 5 575
2
MK-2248

Figure A-1

A.1.2

DDCMP Data Message Format

Error Checking and Recovery

DDCMP uses a 16-bit cycle redundancy check (CRC-16) for detecting transmission errors. When an
error occurs, DDCMP sends a separate negative acknowledge (NAK) message. DDCMP does not re-

quire an acknowledgement message for all data messages. The number in the response field of a normal

header or in either the special NAK or acknowledge (ACK) control message specifies the sequence
number of the last good message received. For example, if messages 4, 5, and 6 have been received
since the last time an acknowledgement was sent and message 6 is bad, the NAK message specifies
number 5 which says “messages 4 and 5 are good and 6 is bad.” When DDCMP operates in full-duplex

///‘e

mode, the line does not have to be turned around; the NAK is simply added to the sequence of messages
for the transmitter.
When
a sequence error occurs in DDCMP, the receiving station does not respond to the message. The

transmitting station detects, from the response field of the messages it receives (or via timeout), that

A-1

the receiving station is still looking for a certain message and sends it again. For example, if the next
message the receiver expects to receive is 5, but receives 6 instead, the receiver does not change the
response field (which contains a 4) of its data messages. The receiver will say, “I accept all messages up
through message 4 and I'm still looking for message 5.”

A.13 Character Coding

DDCMP uses ASCII control characters for SYN, SOH, ENQ and DLE. The remainder of the message, including the header, is transparent.
A.1.4

Data Transparency

DDCMP defines transparency by use of a count field in the header. The header is of a fixed length. The
count in the header determines the length of the transparent information field, which can be from 1 to
16,383 bytes long. To validate the header and count field, it is followed by a CRC-16 field; all header
characters are included in the CRC calculation. Once validated, the count is used to receive the data
and to locate the second CRC-16, which is calculated on the data field. Thus, character stuffingis
avoided.
A.1.5

Data Channel Utilization

DDCMP uses either full-duplex or half-duplex circuits at optimum efficiency. In the full-duplex mode,
DDCMP operates as two independent one-way channels, each containing its own data stream. The only
dependency is the acknowledgements which must be sent in the data stream in the opposite direction.

Separate ACK messages are unnecessary, therefore, reducing the control overhead. Acknowledgements
are simply placed in the response field of the next data message for the opposite direction. If several
data messages are received correctly before the terminal is able to send a message, all of them can be
acknowledged by one response. Only when a transmission error occurs, or when traffic in the opposite

direction is light (no data message to send), is it necessary to send a special NAK or ACK message,
respectively.

In summary, DDCMP data channel utilization features include:'

The ability to run on full-duplex or half-duplex data channel facilities,

Low control character overhead,

-3

‘No character stuffing,

No separate ACKs when traffic is heavy; this saves on extra sync-characters and intermessage gaps,

Multiple acknowledgements (up to 255) with one ACK, and

The ability to support point-to-point and multipoint lines.

A.2 PROTOCOL DESCRIPTION
»
DDCMP is a very general protocol; it can be used on synchronous or asynchronous, half-duplex or fullduplex, serial or parallel, and point-to-point or multipoint systems. Most applications involving protocols
are half- duplex or full-duplex transmissions in a serial synchronous mode; that operatmg environment 1s
empha51zed in the following description.
|

The headeris the most important part of the message because it contains the message sequence numbering information and the character count, the two most important features of DDCMP. Because of
the importance of the header information, it merits its own CRC blockcheck, indicatedin Figure A-2 as
CRC-1. Messages that contain data, rather than just control information, have a second section which
contains any number of 8-bit characters (up to a maximum of 16,383) and a second CRC (md1catedin
Figure A-2 as CRC-2).

NOTE 1
N

|RESPONSE |SEQUENCE |ADDRESS{

COUNT | FLAG

14 BITS| 2 BITS|

8 BITS

INFORMATION

2
CRC1 | ANY NUMBER | CRC
|16 BITS

OF 8-BIT

16 BITS

CHARACTERS
\

XXX

SOH
— DATA MESSAGES
10000001
ENQ{ACKNOWLEDGEMENT
00000101
NEGATIVE ACKNOWLEDGE 00000101

REASONS:

REPLY MESSAGE

ENQ { START MESSAGE

DLE

E
,

XXX

XOOKXXXX

MXOXXXXXXX

CHARACTER COUNT
00000001 000000
00000010---------

QS
QS
QS

RESP #
RESP #
RESP
#

MESSAGE#
00000000
00000000

ADDRESS
ADDRESS
ADDRESS

LSTMESS#

ADDRESS

00000000
00000000

ADDRESS
ADDRESS

000001

BCC DATA ERROR

000010

REP RESPONSE

000011

BUFFER UNAVAILABLE

001000

RECEIVER OVERRUN

001001

MESSAGE TOO LONG

010000

HEADER FORMAT ERROR-

010001

00000101

START ACKNOWLEDGEMENT 00000101
10010000
MAINTENANCE MESSAGE

lore

XXXKOKXHXXXXX

BCC HEADER ERROR

00000101

0000001 1000000

00000000

00000111000000
CHARACTER COUNT

11
11

00000000
00000000

000001 10000000

00000000

ADDRESS

NOTES:

1. ONLY THE DATA MESSAGE AND THE MAINTENANCE MESSAGE HAVE CHARACTER COUNTS, SO
ONLY THESE MESSAGES HAVE THE INFORMATION AND CRC2 FIELDS SHOWN IN THE MESSAGE.
FORMAT DIAGRAM ABOVE.

2. “RESP #" REFERS TO RESPONSE NUMBER. THIS IS THE NUMBER OF THE LAST MESSAGE
RECEIVED CORRECTLY. WHEN USED IN A NEGATIVE ACKNOWLEDGE MESSAGE, IT IS ASSUMED

THAT THE NEXT HIGHER NUMBERED MESSAGE WAS NOT RECEIVED, WAS RECEIVED WITH
ERRORS, OR WAS UNACCEPTED FOR SOME OTHER REASON. SEE “REASONS.”

3. "MESSAGE#" IS THE SEQUENTIALLY ASSIGNED NUMBER OF THIS MESSAGE. NUMBERS ARE

ASSIGNED BY THE TRANSMITTING STATION MODULO 256; |.E., MESSAGE 000 FOLLOWS 255.

4. "LSTMESS#" IS THE NUMBER OF THE LAST MESSAGE TRANSMITTED BY THE STATION. SEE THE

TEXT DISCUSSION OF REP MESSAGES.

5. “ ADDRESS" IS THE ADDRESS OF THE TRIBUTARY STATION IN MULTIPOINT SYSTEMS AND IS

USED IN MESSAGES BOTH TO AND FROM THE TRIBUTARY. IN POINT TO POINT OPERATION, A

STATION SENDS THE ADDRESS “ 1" BUT IGNORES THE ADDRESS FIELD ON RECEPTION.

6 “Q" AND ""S” REFER TO THE QUICK SYNC FLAG BIT AND THE SELECT BIT. SEE TEXT.
MK- 2249

Figure A2 DDCMP Message Format in Detail

In DDCMP, any pair of stations that exchange messages with each other number those messages sequentially starting with message number one. Each successive data message is numbered using the next
number in sequence, modulo 256. Thus, a long sequence of messages would be numbered 1, 2, 3,...254,
255, 0, 1,...255. The first message sequence always starts with a number 1, and every sequence thereafter begins with a 0. The numbering applies to each direction separately. For example, station A might
be sending its messages 6, 7, and 8 to station B, while station B is sending its messages 5, 6, and 7 to
station A. Thus, in a multipoint configuration where a control station is engaged in two-way communication with ten tributary stations, there are 20 different message number sequences involved — one
sequence for messages from each of the ten tributaries to the control station, and one sequence for
messages from the control station to each of the ten tributaries.

Whenever a station transmits a message to another station, it assigns its next sequential message number to that message and places that number in the sequence field of the message header. In addition to
maintaining a counter for the sequentially numbered messages which it sends, the station also maintains
a counter of the message numbers received from the other station. It updates that counter whenever a
message is received with a message number exactly one higher than the previously received message
number. The contents of the received message counter are included in the response field of the message
being sent, to indicate to the other station the highest sequenced message that has been received.

When a station receives a message containing an error, that station sends a negative acknowledge
(NAK) message back to the transmitting station. DDCMP does not require an acknowledgement for
each message, as the number in the response field of a normal header (or in either the special NAK or
positive acknowledgement message ACK) specifies the sequence number of the last good message received.

When a station receives a message that is out of sequence, it does not respond to that message. The
transmitting station detects this from the response field of the messages which it receives; if the reply
interval expires before the transmitting station receives an acknowledgement, the transmitting station
sends a REP (reply) message. The REP message contains the sequence number of the most recent
unacknowledged message sent to the remote station. If the receiving station has correctly received the
message referred to in the REP message (as well as the messages preceding it), it replies to the REP by
- sending an ACK. If it has not received the message referred to in sequence, it sends a NAK containing
the number of the last message that it did receive correctly. The transmitting station then retransmits
all data messages after the message specified in the NAK.
|
-

The numbering system for DDCMP messages permits up to 255 unacknowledged messages outstanding; a useful feature when working on high-delay circuits such as those using satellites. However,
the DMV11 limits the maximum number of unacknowledged messages outstanding to be 127.
A.3

MESSAGE FORMAT

With the above background, it is now time to explore the various DDCMP message formats in full
detail, as shown in Figure A-2. The first character of the message is the class of message indicator,
represented in ASCII with even parity. There are three classes of messages; data, control, and maintenance. These are indicated by class of message indicators SOH, ENQ, and DLE, respectively. The next
two characters of the message are broken into a 14-bit field and a 2-bit field. The 14-bit field is used in
data and maintenance messages to indicate the number of characters that follow the header CRC field
and form the information part of the message. In control messages, the first eight bits of the 14-bit field
are used to designate what type of control message it is; the last six bits are generally filled with zeros.
The exception is in NAK messages where the last six bits are used to specify the reason for the NAK.
The 2-bit field contains the quick-sync and select flags.

A-4

Before the message format is discussed in greater detail, the message sequencing system should be explained because most of the header information is directly or indirectly related to the sequencing operation.

The quick-sync flag is used to inform the receiving station that the message will be followed by synccharacters; the receiver may wish to set its associated synchronous receiver hardware into sync-search
mode and sync-strip mode. This reestablishes synchronization and syncs are discarded until the first
- character of the next message arrives. The purpose of this is to permit the receiving station to engage
any hardware sync-stripping logic it might have and prevent it from filling its buffers with sync-characters. The select flag is used to control link management in half-duplex or multipoint configurations
where transmitters need to get turned on and off.

Link management is the process of controlling the transmission and reception of data on links where
there may be two or more transmitters and /or receivers actively connected to the same signal channels.
This is true of half-duplex point-to-point links, as well as full- and half-duplex multipoint links. On halfduplex links, only one transmitter may be active at a time; on full-duplex links, only one slave transmitter may be active on the link at a time.

A station on such a link may transmit when it has been selected or granted ownership of the link. This
ownership is passed by use of the select flag existing in all messages. A select flag set in a received
message allows the addressed station to transmit after completing reception of the message. The select
flag also means that the transmitter ceases transmitting after the message is sent.
The response field contains the number of the last message correctly received. This field is used in data
messages and in the positive and negative acknowledge types of control messages. Its function should be
evident from the preceding discussion of sequence control.
|

The sequence field is used in data messages and in the REP type of control message. In a data message,
it contains the sequence number of the message as assigned by the transmitting station. In a REP message, it 1s used as part of the question, “Have you received all messages up through message number
(specify) correctly?”
The address field is used to identify the tributary station in multipoint networks and is used in messages
both to and from the tributary. In point-to-point operation, each station uses an address of 1.
In addition to the positive and negative acknowledgement and REP types of control messages, there are
also start and start acknowledge control messages. These are used to place the station which receives
them in a known state. In particular, they initialize the message counters, timers, and other counters.
The start acknowledge message indicates that this has been accomplished.
Figure A-2 also shows the maintenance message. This is typically a bootstrap message containing load
programs in the information field. A complete treatment of maintenance messages and start-up procedures is beyond the scope of this book.
NOTE
Refer to the DDCMP specification order (AAD599A-TC) for a complete detailed description of
DDCMP.

APPENDIX B
FLOATING DEVICE

AND VECTOR ADDRESSES

B.1

FLOATING DEVICE ADDRESSES

UNIBUS and LSI-11 addresses, starting at 760010 and continuing through 763776, are designated as
floating device addresses (see Figure B-1). These are used as register addresses for communications
(and other) devices interfacing with the PDP-11 (refer to Table B-1).
|

NOTE
Some devices are not supported by LSI-11; however,
the same scheme applies. That is, gaps are provided
as appropriate. The convention for assigning these

addresses is as follows:

A gap of 10g must be left between the last address of one device type and the first address of the next
device type. The first address of the next device type must start on a modulo 10g boundary. The gap of
10g must also be left for devices that are not installed but are skipped over in the priority ranking list.
Multiple devices of the same type must be assigned contiguous addresses. Reassignment of device types
already in the system may be required to make room for additional ones.

B.2
FLOATING VECTOR ADDRESSES
Vector addresses, starting at 300 and proceeding upward to 777, are designated as floating vectors.

These are used for communications (and other) devices that interface with the PDP-11 and VAX-11.
Multiple devices of the same type would be assigned vectors sequentially (refer to Table B-2).

NOTE
Some devices are not supported by LSI-11; however,
the same scheme applies. Vector size is determined
by the device type.

There are no gaps in floating vectors unless required by physical hardware restrictions (in data communications devices, the receive vector must be on a zero boundary and the transmit vector must be on a
43 boundary).
-

B-1

777 777

DIGITAL EQUIPMENT

WORDS

CORPORATION
(FIXED ADDRESSES)

770 000

1K
WORDS

" DR11-C

767 777

4
USER ADDRESSES

764 000
763 777

)

WORDS

FLOATING ADDRESSES
DIGITAL EQUIP CORP (DIAGNOSTICS)

760 010
760 006

760 000
757 777

001 000

000 777

VECTORS

FLOATING VECTORS
000 300

000 277

48
VECTORS

TRAP & INTERRUPT
VECTORS
000 000

MK-2190

Figure B-1

UNIBUS and LSI-11 Address Map

Table B-1

Rank

Option

Decimal
Size

DJ11

207

3
4
5
6

DQI11
DUI11
DUPI11
LK11A

4
4
4
4

10
10
10
10

8
9
10
11

DZ11* and DZV11/DZ32
KMCI11
LPP11
VMV21

4
4
4
4

10
10
10
10

13
14
15
16
17

DWR70
RLI11 and RLV11
LPA11-K
KW11-C
Reserved

4
4
8
4
4

10
;
10 (extra only)
20 (extra only)
10
10
|

18
19
20
21
22
23
24

RX11
DR11-W
DR11-B
DMPI11-AD
DPV11
ISB11
DMYVI11-AD

4
4
4
4
4
4
8

10 (extra only)
10

,/ ’A\\

Floating CSR Address Devices

DHI11

DMCI11/DMRI11

VMV3l1

Octal
Modulus
10

20t

10 (after second)
10
10
10
20

*DZ11E and DZI11F are dual DZ11s and are treated by the algorithm as two DZ11s.
TStarting CSR address must be an even multiple of 20 (octal).

Table B-2

|
Rank

Option

1
2

DCl11
KL11 (extra)

2
2
3
4
5
6
7
8
9

Floating Interrupt Vector Devices

DL11-A (extra)
DL11-B (extra)
DP11
DMI11-A
DNI11
DMI11-BB
DH11 modem control
DRI11-A
DR11-C

Decimal
Size

Octal

4
4
4
4
4
4
2
2
2
4
4

10
10*
10*
10
10
10
4
4
4
10*
10*

Modulus

*The vector for the device of this type must always be on a 10g boundary.

Table B-2

Floating Interrupt Vector Devices (Cont)

Decimal
Size

Octal
Modulus

Rank

Option

PA611 (reader & punch)

10*

11
12
13

LPDI11
DTI11
DX11

4
4
4

10
10*
10*

DL11-C

10*

DL11-D

10*

DL11-E

10*

DJ11

10*

DHI11

107

GT40/VSV11

LPS11

10*
107

DQ11

KW11-W

21
22

DUI11
DUPI11

4
4

10*
10*

DV and modem control

LK11-A

DWUN

DMCI11/DMR11

10*

DZ11/DZ32/DZV11

10*

KMCl11

29
30

LPP11
VMV2]

4
4

31
32

VMV3l1
VTVO0l1

4
4

10
10

DWR70

10*

34
35

RLI1/RLVI1I
TSI11

2
2

4
4 (after the first)

36
37
38

LPA11-K
IP11/IP300
KWI11-C

4
2
4

39
40
41
42
43
44
45
46

RX11/RX211
DR11-W
DR11-B
DMP11-AD
DPV11
MLI11
ISB11
DMVI11-AD

2
2
2
4
4
2
4
4

10
10

4 (after the first)
4
4 (after the first)
10
10
4 (MASSBUS device)
10
10

*The vector for the device of this type must always be on a 10g boundary.

TThese devices can have either a M7820 or M7821 interrupt control module. However, it should always
be on a 10g boundary.

B.3 EXAMPLES OF DEVICE AND VECTOR ADDRESS ASSIGNMENT
This example has devices that require device and vector address assignment in the floating address space.
The devices are:

1 RLV11/RLV12

2 DPVlIls
| DMVII

Device

Address

(Option)

Vector

Address

760010
760020
760030
760040
760050
760060
760070
760100
760110
760120
760130
760140
760150

RLVI1I

760160
760170

Gap left for DJ11
Gap left for DH11
Gap left for DQ11
Gap left for DU I
Gap left for DUPI 1
Gap left for LKI11A
Gap left for DMCI11/DMRI1 1
Gap left for DZ11/DZV11
Gap left for KMCI1 |
Gap left for LPP11
Gap left for VMV21
Gap left for VMV31
Gap left for DWR70

300

760200
760210
-

DPVI11
DPVI1

760220
760230
760240
760250
760260
760270
760300
760310

310
320

‘DMVI1I

760320
760340
760360

Comment

Second RLV11/RLV12
Gap left between RLV11 and next
device
Gap left for LPA11-K
Gap left for KW11-C
Reserved
Gap left for RX11
Gap left for DR11-W
Gap left for DR11-B
Gap left for DMP11
First DPV11
Second DPV11
Gap left between DPV 1 and next
device

330

Gap left for ISB11
First and only DMV11
Gap left after last device, in this

case the DMV11, to indicate that no

other devices follow

APPENDIX C

MODEM CONTROL REGISTER FORMATS

C.1
MODEM CONTROL REGISTER FORMATS
The modem signals made available by the DMV11 can be examined or modified by the user program if
needed. This supplies the flexibility needed to meet the various modem interface requirements of different countries.

READ MODEM STATUS
BSELA4:
Bit

Name

Description

CARRIER

Received line signal detector, commonly referred to as carrier detect, indicates that there is an appropriate audio tone being received from the remote modem. Typically, in full- and half-duplex
applications,
carrier
detect
is
on
whenever
the
communications line is intact and the remote modem has the signal request to send asserted (the modem is transmitting). This
signal is also applicable to the DMV11 integral modem.

NOT USED

ALWAYS READ AS ZERO.

CLEAR TO SEND

This signal is generated by the local modem to indicate whether
or not it is ready to transmit data. Clear to send is the local

modem’s response to the asserting of request to send. This signal
has a slightly different meaning with different modems. With

some modems it indicates that the carrier is being received from
the remote modem, and, therefore, is an indication that a suitable
communications channel exists.
3

MODEM READY

This signal indicates that the modem is ready to operate. The ON
condition indicates that the local modem is connected to the communications line and is ready to exchange further control signals
with the DMVI11. The OFF condition indicates that the local

modem is not ready to operate. This signal, when implemented by
the modem, is used by the DMV11 to detect either a power-off
condition or a cable-related modem malfunction.
4

HALF-DUPLEX

This signal, when asserted, indicates that the DMV11 is in the

half-duplex mode. This means that the DMV11 is connected to a
communications line designed for transmission in either direction, but not in both directions simultaneously. When cleared, it
implies full-duplex operation which is two-way independent transmission in both directions.

C-1

Name

Description

REQUEST TO SEND

This signal serves to control the data channel transmit function of
the local modem, and on a half-duplex channel, to control the direction of data transmission of the local modem. On a full-duplex
channel, the ON condition maintains the modem in the transmit
mode, and the OFF condition maintains the modem in the nontransmit mode. On a haif-duplex channel, the ON condition
maintains the modem in the transmit mode and inhibits the receive mode. The OFF condition maintains the modem in the receive mode. A transition from OFF to ON instructs the modem to
enter the transmit mode. The modem responds by taking such action as may be necessary and indicates completion of such actions
by asserting clear to send, thereby, indicating to the DMV11 that
data may be transferred across the communications channel. A
transition from ON to OFF instructs the modem to complete the
transmission of all data that was previously transferred to the
modem and then assume a nontransmit or receive mode, whichever is appropriate. The modem responds to this instruction by
turning OFF the signal clear to send when it is again prepared to
respond to a subsequent ON condition of request to send.

DATA TERMINAL
READY

This signal controls the switching of the local modem to and from
the communications line. When asserted, this signal serves to inform the local modem that the DMV11 is ready to operate. This
signal also prepares the modem for connection to the communications line and maintains this connection as long as it is ON.
When turned OFF, this signal causes the local modem to disconnect after all data previously transferred to the modem has
been transmitted. This signal can be used by the local modem to
detect a power-off condition in the DMV11 or a cable-related
modem malfunction.

RING

This signal indicates whether an incoming call signal is being received by the local modem. When ON, this signal indicates that
an incoming call (ringing) signal is being received by the local
modem. The ON state of ring must appear approximately at the
same time as the ON segment of the ringing cycle (during rings)
on the communications line. The OFF condition must be maintained during the OFF segment of the ringing cycle (between
rings) and at all other times that ringing is not being received.
This signal is not affected by the state of data terminal ready.

READ MODEM STATUS
BSELS
Bit

Name

MODE

Description

This bit indicates the operational mode of the line unit. A one indicates character-oriented protocol operation, and a zero indicates bit-oriented protocol operation. The DMVI11 initializes
this bit to one.

C-2

| /@h\\-

Bit

Name

Description

NOT USED

ALWAYS READ AS ZERO.

TEST MODE

This signal indicates whether or not the local modem is in a test
condition. (This signal applies only to modems that support this
feature.) When in the ON condition, this signal indicates to the
DMYV11 that the local modem has been placed in a test condition.
The ON condition can also be in response to either local or remote activation by means of any other modem test condition. Activation of a telecommunications network test condition (for example, facility loopback) that is known to the modem can also
cause this signal to be ON. In the OFF condition, this signal indicates that the modem is not in the test mode and is available for
normal operation.
ALWAYS READ AS ZERO

NOT USED

ALWAYS READ AS ZERO

NOT USED

ALWAYS READ AS ZERO

NOT USED

ALWAYS READ AS ZERO

NOT USED

ALWAYS READ AS ZERO

NOT USED

WRITE MODEM CONTROL
BSELA4

Bit

Name

NOT USED

Description

SELECT STANDBY

Defaulted to 0 by DMV11 hardware.

MAINTENANCE

Defaulted to 0 by DMV11 hardware.

MAINTENANCE
MODE 1

Defaulted to 0 by DMVI11 hardware.

HALF-DUPLEX

The DMYV11 uses this bit'to place the line unit into the half-duplex mode. The user program cannot set or clear this bit. The
DMV11 can change line characteristics only through the mode
definition command. The DMV11 is equipped with a software interlock that prevents simultaneous transmission and reception
when in the half-duplex mode. While the transmitter is transmitting, the receiver is disabled from receiving data via a hardware interlock.

SELECT
FREQUENCY

This signal is used to select the transmit and receive frequency
bands of a modem. In the ON condition, the higher frequency

MODE 2

C-3

Bit

Description'

Name

band is selected for transmission to the communications channel,
and the lower frequency band is selected for reception from the
communications channel. When OFF, the lower frequency band
is selected for transmission to the communications channel, and
the higher frequency band is selected for reception from the communications channel.
NOTE
The modem, if it supports select frequency, must be
set up to ignore this signal from DMV11.

DATA TERMINAL
READY

This signal controls switching of the local modem to and from the
communications line. When asserted, this signal serves to inform
the local modem that the DMV11 is ready to operate. This signal
also prepares the modem for connection to the communications
line and maintains this connection as long as it is ON. When
turned OFF, this signal causes the local modem to disconnect after all data previously transferred to the modem has been transmitted. This signal can be used by the local modem to detect a
power-off condition at the DMV11 or a cable-related modem

This signal determines whether or not the local modem will rapidly respond to new data on the communications line. This signal 1s
used at control stations in multipoint networks where the remote
modems operate in switched-carrier
mode. This incoming signal
to the control station appears as a series of short message bursts
transmitted by each tributary as it responds to the poll from the
control station. In order to permit rapid accommodation to signals from several tributaries appearing in quick succession, the
control station informs the local modem when a new signal is
about to begin by asserting polling for a brief interval. For synchronous systems, clock timing on the incoming message varies
from message to message because the remote modems are in no
way synchronized to each other. If the time interval between messages is too short, the clock holdover after the end of one message
may preclude rapid synchronization on the following message.
The use of this signal allows the control station to reset the
modem receiver timing recovery circuit, enabling it to respond
more quickly to the line signal present after polling has been
turned OFF. This signal applies only to modems that support polling.

C.2

RS-449 VERSUS RS-232-C

The most common interface standard in use during recent years is RS-232-C. However, when used in
modern communications systems it has critical limitations; the most serious being speed and distance.
For this reason, the interface standard RS-449 was developed to replace RS-232-C. This standard maintains a degree of compatibility with RS-232-C to accommodate an upward transition to RS-449.

The most significant difference between RS-449 and RS-232-C is the electrical characteristics of sig-

nals used between the data communications equipment (DCE) and the data terminal equipment
C-4

TN-

NEW SIGNAL

malfunction.

(DTE). The RS-232-C standard specifies only unbalanced circuits, whereas, RS-449 specifies both balanced and unbalanced circuits. The specifications for these two circuit types supported by RS-449 are
contained in EIA standards RS-422-A for balanced circuits and RS-423-A for unbalanced circuits.

These new standards permit greater transmission speeds and allow greater distance between the DTE

and DCE. The maximum transmission speeds supported by RS-422-A and RS-423-A specified circuits
vary with circuit length. The normal transmission speed limits are 20K b/s for RS-423-A at 61 m (200
feet) and 2M b/s for RS-422-A also at 61 m (200 feet). These normal transmission speeds can be varied
by tradeoffs between speed and distance.

Another major difference between RS-449 and RS-232-C is the specification of two new connectors to
- accommodate the leads required to support additional circuit functions and the balanced interface circuits. One connector is a 37-pin cinch used to accommodate the majority of data communications applications. The other is a 9-pin cinch for applications requiring secondary channel functions. Some of the
new circuits implemented by RS-449 support local and remote loopback testing and standby channel
selection.

The transition from RS-232-C to RS-449 will not happen immediately. Therefore, applications that re- |
quire connection between RS-232-C and RS-449 interfaces must adhere to the limitations of RS-232-C,
which specifies a normal transmission speed
of 20K b/s at a maximum distance of 15.2 m (50 feet).
DMV11 does not support RS-422-A balanced circuits.

APPENDIX D
MODEM CONTROL

D.1

MODEM CONTROL

There are two levels of modem control available to the DMV11. The first level is provided by the hardware, and the second by the DMV11 microcode.

D.1.1 Hardware Modem Control
The DMV11 provides the following modem control function:

Prevention of simultaneous transmission and reception in half-duplex mode.

Half-Duplex Mode - When set, HALF-DUPLEX specifies that the DMV11 is in the half-duplex mode.
In half-duplex mode, a hardware interlock prevents
theDMV11 from transmitting and receiving simultaneously.
NOTE

This hardware lockout prevents the DMV11 from
being used in the half-duplex mode on a full-duplex
modem with the continuous carrier option installed.

D.1.2 Modem Control Implemented by the DMV11 Microcode
The modem control signals implemented by the DMV11 are:
Modem ready (data set ready),
Request to send/clear to send,
Carrier,

Data terminal ready, and

Auto answer.

Each of these signals are outlined in Table D-1.
Once modem ready goes ON, the DMV11 reports any transition from ON to OFF to the user program
by issuing a control response containing the code for the system-event modem disconnect. The microcode tests that modem ready is OFF for 10 ms. Transmission is initially inhibited by the microcode by
interlocking the signals modem ready and request to send.

Whenever the signal carrier detect is dropped by the modem for greater than 1.28 seconds, the user
program is notified by a control response containing the code for the system event modem carrier loss.
Diagrams are used in the discussion of modem control functions. Refer to Figure D-1 as an aid in inter-

preting these diagrams. The flow depicted by the diagrams (Figures D-2 through D-8) describes the pro-

cessing of EIA modem control signals by the DMV11. Each diagram represents a serial flow for a specific modem control function. However, the functions performed, as represented by each diagram, are
performed in parallel. The readable and writeable modem signals listed on the diagram for modem status can be read and written through the control command using the request keys read modem status
and write mode control.

D-1

Table D-1

Signal
~Data Set Ready—
Modem Ready:

DMV11 Modem Control Functions

Description

Software interlock prevents the DMV11 from transmitting if DSR is not
returned. If DSR drops (meaning that it once was asserted) for a period
of 10 ms, the transmitter and receiver are resynchronized, the transmitter
and receiver sections of the microcode are reset to the idle state to allow
the user to return buffers, DTR is then dropped to clear the line (see
DTR for reasserting conditions), and the user is then notlfled of the DSR
drop via a control-out for disconnect.
Software interlock preventing the DMVI11 from transmitting if DSR is
not returned: If the DMV11 has been instructed by the user to start up
the communications line, and DSR is not asserted, the DMV11 does not
transmit. There is no timer started for the first assertion of DSR. It is the
responsibility of the user to ensure that the modem is plugged in. Also, if
the modem is a dial-up modem, the user should make sure that the number is dialed. In most cases the start command is issued with the intent of
waiting for an incoming call. In this case, the timer value is arbitrary so
that it has been left up to the user software to determine this timeout. If
data terminal ready (DTR) is not asserted because of a past error condition that caused the dropping of DTR (that is, disconnect), the user program may assert DTR via the write modem command to enable transmis-

sion.

Request to Send/
Clear to Send:

For all applications: Before RTS is asserted (if already asserted this is
bypassed) CTS is checked for the “ON” condition. If CTS is “ON”, a
10-20 ms timer is started while waiting for CTS to drop. If CTS does not
drop within the timer period, constant CTS is assumed and RTS is set.

For all applications: Software interlock prevents transmission if CTS 1s
not returned. IF CTS is not returned within 30 seconds (plus or minus 10
ms), a disconnect control-out is queued with a CTS failure code in
BSEL7. The transmitter and receiver are resynchronized, the transmitter
and receiver sections of the microcode are reset to the idle state to allow
the user to return buffers, and DTR is then dropped to clear the line. (See
DTR for reasserting conditions).

For all applications: During the time that RTS is set, every 10 ms CTS is
checked for the “ON”’ condition. If CTS stays in the “OFF”’ condition for
30 seconds (plus or minus 10 ms), a disconnect control out is queued with
a CTS failure code in BSEL7. The transmitter and receiver are resynchronized, the transmitter and receiver sections of the microcode are
reset to the idle state to allow the user to return buffers, and DTR is then
dropped to clear the line. (See DTR for reasserting conditions).
For all half-duplex applications: The setting of request to send 1s “ANDED” with the half-duplex bit in the hardware to “blind” the receiver
when transmitting.

Table D-1

DMV11 Modem Control Functions (Cont)

Signal

Description

Carrier:

Software interlocks prevent transmission in half-duplex if carrier is in the
“ON” condition. This prevents the DMV11 from running half-duplex on
four-wire constant carrier modems.
For all applications: Hardware interlock of carrier and the receiver clock
stop the USYRT from receiving if carrier were to drop in the middle of a
message.

For all applications: If carrier ““drops” while the DMV11 is in the process
of receiving the carrier, the loss timer is started. If the carrier loss timer
expires (1.28 second interval), the user is notified via a control-out for
carrier loss. The receiver is then resynchronized and the receiver microcode is reset to the waiting state for the next message. If the carrier loss is
less than 1.28 seconds (carrier is reasserted before the timeout), the message being received is allowed to finish. If CRC errors are detected (normal case), the protocol recovers from the failure.
Data terminal ready:

DMVI1I1 clears DTR on a power-up bus initialization, and a master clear.
This is a hardware function. DTR is not gated from the interface drivers
when the DMV11 is placed in loopback mode. DTR is monitored by diagnostics running in internal loopback to ensure that the microcode does not
set it.
»

When DTR is dropped because of errors, it is only reasserted if any of the
following conditions exist: auto answer is enabled or remote load detect is
enabled. The code is in the process of power-on boot or request boot.
Auto Answer:

This option is switch selectable. If enabled, the DMV11 asserts DTR and
waits for modem ready (DSR). Because of the difference between
modems in the U.S. and other countries, ring is not used as an indication
that an incoming call has been established. As it stands, DSR is the indication that the call has been established. If a valid DDCMP message is
not received within 30 seconds (plus or minus 10 ms) after a connection is
established, DTR is dropped (hang up the phone). The connection is considered to be established on assertion of carrier or clear to send. The
transmitter and receiver are resynchronized, the transmitter and receiver
sections of the microcode are reset to the idle state, and DTR is then reasserted after DSR drops (or in 10 seconds whichever comes first). In this
case the user is not notified of the cancelled call. An internal counter is
incremented te log the incoming calls (latches at 256) and is available for
reading by the user program.

D-3

CONDITIONS TO BE SATISFIED. IF CONDITIONS ARE NOT
MET SERIAL FLOW DOES NOT CONTINUE.

ACTIONS PERFORMED BY DMV11.

MK-2657

Figure D-1

Flow Diagram Symbology

)

‘ /’

ENTRY OR EXIT SYMBOLS

D-4

(

POWER ON

SYSTEM

[2.4]

POWER ON

INITIALIZATION

[2.4]

CLEAR DTR

] [2.5]

DEVICE

MASTER CLEAR [2.4]

BOOT ENABLED

(SWITCH)

USER ISSUES

MODE DEFINED

BOOT

MODE DEFN

IN SWITCHES

a7 Se7

1261

COMMAND

[2.2]

[2.2]
|

SET DTR

SET CALTMR

SET DTR

SET CALTMR

= ON

| seTe/mor

(

23]

USER REQUEST

CALTMR

MODEM STATUS

— ON

READ/WRITE

()

DSR = ON

DSR = ON
CD = ON

[

DSR = ON

[

]

( MODSTAT )

SCAN FOR

CALTMR

(

REMOTE

[2.1]

LOAD

MIESSAGE

VALID

MESSAGE

(2.3]

‘

MESSAGE TO

DSR = ON TO

SENT

OFF

SET P/MOP j

(

FOR

RECEIVE )

10mSEC

|
NOTIFY USER OF

P/MOP = ON

DSR DROP

P/MOP = OFF

DISCONNECT

—————»@

(CONTROL RESPONSE)

(
,

‘

TRANSMIT2

)

—-( TRANSMIT

)

NOTES:
[2.1] REMOTE LOAD DETECT IS A MAINT. DDCMP MESSAGE INITIATING A DOWN LINE LOAD.

[2.2) CALTMR

- (CALL TIMER): USED TO DETERMINE IF VALID MESSAGE IS RECEIVED. "ON" INDICATES TIMER

RUNNING.

[2.3] P/MOP - PRIMARY MAINTENANCE OPERATION PROTOCOL, REQUESTING REMOTE LOAD.
(2.4] RUN COMPLETE MICRODIAGNOSTICS (MICROPROCESSOR AND LINE UNIT)
[2.5] HARDWARE FUNCTION
[2.6] INVOKE PRIMARY MOP BOOT (BIT FIVE, BSEL 1)
MK-2705

Figure D-2

Modem Control (Start)

D-5

( -TRANSMIT ) '

HALF-DUPLEX

FULL-DUPLEX

!
RECEIVER NOT

NO LINE ERRORS

LINE ERRORS

ACTIVE

ENCOUNTERED

ENCOUNTERED
©r

!
CARRIER WAIT

TIMR <1 SEC

311

cLearrTs

CD = OFF

CWTIMR

| CTS TIMER =1 SEC |
; (3.2]

ASSERTATS |

CTS TIMR «—

CTS =0

30 SEC

NOTIFY USER OF

CTSTMR =0

STREAMING

STATION
CTS=ON

CTS TIMR=0

CD = OFF
\

NOTIFY USER

OF CTS FAILURE
RTS=OFF

RTS = ON

CSH ut DOWN)

CTS TIMER 20ms
TRANSMIT

CTS=O0FF

CTS TMR=0

END OF TRANS

CTS=O0OFF

FDX

CTS TIMR <-—

HDX

10 SEC

‘

TIMR=0

CLEAR RTS

CTS=ON
CANCEL CTS TIMR

NOTIFY USER OF

CTS FAILURE

@UT Dow@
NOTES:

-- CARRIER WAIT TIMER. IT DETECTS THE CONDITION WHERE THE LINK WAS NOT RELINQUISHED IN
[3.1] CWTIMR
'

TIME BY THE REMOTE END.

[3.2] CTSTMR -- CLEAR TO SEND TIMER. TIME CLEAR TO SEND GOING AWAY WHEN DROPPING RTS BECAUSE OF LINE
ERRORS. FALL-OUT COVERS CONDITION OF CONSTANT CTS MODEMS.

[3.3] IN FULL DUPLEX MODE -- DMP11 ASSERTS RTS CONSTANTLY. RTS IS DROPPED ONLY WHEN THERE ARE LINE
ERRORS.

[3.4) SOFTWARE INTERLOCK - CONDITION IS SWITCH SELECTABLE FOR CONSTANT CTS MODEMS.
MK-2706

Figure D-3

Modem Control (Transmit)
D-6

CTRANSMIT 2 )

LESS THAN 24 REQUEST

24 REQUEST REMOTE PROGRAM

REMOTE PROGRAM LOAD

LOAD MESSAGES SENT

MESSAGES SENT

| TIMER=-10 SEC|

| TIMER--3 SEC ]
o

TIMER=0

'
C TRANSMIT

CLEAR DTR

Y
TIMER=0

seTotR

MK-2703

Figure D-4

Modem Control (Transmit 2)

‘

( RECTIVE 3

HALF-DUPLEX

FULL-DUPLEX

TRANSMITTER NOT
ACTIVE

IN HALF DUPLEX, LINE UNIT |
PROVIDES INTERLOCK TO

ENABLE RCV CLOCK ONLY IF

TRANSMITTER IS IDLE.
(RTS =OFF)

CD = ON

SYNC'ED ON NEW
FRAME

START TO RECEIVE

]—l
.
CD = OFF

CD DROPPED IN THE
MIDDLE OF DATA
STREAM

!
RESET CDTIMR
TO 1.28 SEC

CD = ON

CDTIMR =0

NOTIFY USER OF
CARRIER LOSS
e

(CONTROL RESPONSE)

END OF

RECEIVE

| RESET RECEIVERJ

MK-2704

Figure D-5

Modem Control (Receive)

( MOD STAT )

6.1]

READ MODEM

WRITE MODEM

STATUS

6.2]

NS
6.1]

READABLE MODEM SIGNALS:

CARRIER
CLEAR TO SEND
MODEM READY (DSR)
HALF DUPLEX
REQUEST TO SEND
DATA TERMINAL READY
RING

(6.2]

WRITEABLE MODEM SIGNALS:
DATA TERMINAL READY

TEST MODE
MK-2702

Figure D-6

Modem Control (Modem Status)

< CALTMR )
|

| START 65 SEC CALL TIMER]

VALID MESSAGE

CALL TIMER = 0O

RECEIVED FOR
THIS STATION

;

+
|

rCLEAR DTR'j

SET CALTMR

= OFF

RESET RECEIVER
AND
TRANSMITTER

| TIMER~-10 SEc|

TIMER = 0

SETDTR

]

NOTE: CALTMR = ON

MK-1967

Modem Control (Call Timer)

/«mm\\

Figure D-7

(SHUT DOWN)

CLEAR DTR I

AND RTS

RESET RECEIVER
AND TRANSMITTER

BOOTING

REMOTE LOAD

CALL TIMR=ON

DETECT

anglil.

[

TIMR<«—10 SEC

TIMR=0

SET DTR

MK-2668

Figure D-8 Modem Control (Shutdown)

D-11

APPENDIX E

QMA DMV11

OPTION CONFIGURATIONS

E.1

INTRODUCTION

This appendix lists the option variations and cabinet kits available for the QMA DMVI11 Synchronous
Controller module. The method for assigning DMV 11 option designations is also described.
The communications option designations enable DIGITAL customers to obtain communication options
~ that are custom-tailored to their particular needs. FCC regulations require that all system cabinets
manufactured after October 1, 1983, and intended for use in the United States, be designed
to limit
electromagnetic interference (EMI). Since both shielded and unshielded cabinets exist in the field, Digital
Equipment Corporation provides separate communication options for each cabinet type.
~

E.2

OPTION DESIGNATION CONVERSION

Since former DMV11 configurations are discontinued or changed to MAINTENANCE ONLY status,
the new option designations must be used to obtain the necessary equipment. Table E-1 can be used to
determine which communication optlon designations to use when designing or expanding upon a computer
system.

Communication options may be obtained by'cust'omers_ either at the time a system is purchased (a factoryinstalled system option) or as an upgrade to an existing system in the field (a field upgrade).
E.2.1

Factory-Installed System Optlons

A factory-installed system option is identified by a single option designation. When this demgna‘uon 1S
specified (see Table E-1), the appropriate module(s), cable(s), and distribution panels are installedin the
particular system being constructed.
E.2.2

Field Upgrade Options

A field upgrade is identified by two option demgnatwns a base option de&gnatmn and a cabinet kit
designation (see Table E-1).
|
,

E.2.2.1 Base Options — The base option designation specifies the electronic module(s) and option
documentatlon

E.2.2.2 Cabinet Kits — The cabinet kit designation specifies the internal cable, the distribution panel, and
an adaptor bracket for installing the distribution panel in a non-FCC compliant cabinet may be included.
External cables needed to connect to a modem or other external device are usually not included.
E.3

OPTION CONFIGURATION SUMMARY

Communication option designations ensure that the proper cable(s), dlstrlbutlon panels, and adaptor
brackets (if necessary) are shipped with each base option.

E-1

Table E-1

OLD OPTION

Option Compatibility Cross-Reference

EQUIVALENT NEW OPTION

Field Upgrade

System Option

Base Option

Cabinet Kit

DMVI11-AA

DMV11-M

CK-DMV1 1-A(’-")1

DMV11-AP2

DMV11-AA

DMV11-M

CK-DMV11-F(*)

DMV11-FP

(RS-232-C)

(RS-423-A/449)
DMVI11-AB
(V.39)

|
-

DMVI11-AC
(Integral Modem)

DMV11-M

CK-DMV11-B(*)

DMV11-BP

DMV11-N

CK-DMV11-C(*)

DMV11-CP

NOTE
The last character of the cabinet kit (*) varies
depending on which kit is required (refer to
Table E-3).
|

The last character of the system option designation is always “P”. This specifies that the
option is to be factory installed. |

Communication options may be obtained by customers either at the time a system is purchased (a factory-

installed system option) or as an upgrade to an existing system in the field (a field upgrade).
The basic designations refer to:
®

System options (factory installed).

Base options and cabinet kits (field upgrades).

System options are installed at the factory and are configured for the particular cabinet in which the
option is being installed.
Base options and cabinet kits are ordered as upgrades to systems already existing in the field. A base

option and cabinet kit together make a complete field upgrade option (that is; a base option designation
and a cabinet kit designation must both be specified to obtain a complete field upgrade).
NOTE
A field upgrade option alone does not make an
unshielded cabinet

FCC compliant. Shielded cabinets

are specially constructed to limit EMI.

E-2

E.3.1

System Option Designations

System option designations provide the following information (Figure E-1):

DMV11-A P

THE DEVICE NAME (THAT IS, DMV11)

THE INTERFACE TYPE IDENTIFIER (TABLE E-2)

j ‘

SPECIFIES FACTORY INTEGRATION.

Figure E-1

System Option Designation

E.3.2 Base Option Designations |

- Base option designations provide the following information (Figure E-2):

THE DEVICE NAME (THAT IS, DMV11)

DMV11-M

1 |T

/,/‘\4

SPECIFIES A BASE OPTION (TABLE E-2)

Figure E-2

FElectrical and Mechanical Interface Type

Table E-2

Base Option Designation

Character

Interface Type

RS-232-C (with full modem control)
V.35

C
F
M, N

Integral modem
RS-423-A /449
Base option

E.3.3 Cabinet Kit Designations
o
Cabinet kits enable customers to custom-tailor communication options to their particular cabinet. Cable
lengths, distribution panels, and method of installation may vary depending on the cabinet kit obtained.

Cabinet kits are individually tailored to specific cabinet types. This enables customers to install communication options in both shielded (FCC compliant) and unshielded (non-FCC compliant) cabinets.

Cabinet kits include:

e
e
®

[Internal cable(s).
Distribution panel.
An adaptor bracket (if necessary).

The internal cable connects the module to the distribution panel which is installed in an I/O bulkhead.

Typically, external cables needed to connect to a modem or other external device are not supplied with the
option and must be ordered separately.

Cabinet kit designations have two characters following the device name (Figure E-3).
CK-DMV11-FA
A\

SPECIFIES CABINET KIT

THE DEVICE NAME (THAT IS, DMV11)

THE INTERFACE TYPE IDENTIFIER (TABLE E-2) THE CABINET IDENTIFIER * (TABLE E-3)

*THE CABINET IDENTIFIER INDICATES WHICH CABLE
LENGTHS ARE SUPPLIED WITH THE CABINET KIT.

TK-11342

" Figure E-3 Cabinet Kit Designation

Table E-3 Cabinet Kit Components
Cabinet
Identifier

|
|
|
Component Parts Supplied

A 53.34 cm (21 in) internal cable (see Note 1)
A distribution panel (PDP-11/23S) (see Note 2)

o
e

A 30.48 cm (12 in) internal cable (see Note 1)
A distribution panel (Micro-11) (see Note 2)

A 76.20 cm (30 in) internal cable (see Note 1)

A distribution panel (PDP-11/23+) (see Note 2)
NOTE

Integral modem versions use 70-18250/70-

RS-232-C version uses 70-20863 panel

20862 cable/panel; all others use BC08S cable.

V.35 version uses 70-20864 panel

RS-423-A/ 449 version uses 70-20864 panel
TN

(

E4 DMV11 OPTION CONFIGURATIONS
Table E-4 provides a reference to other option configurations that are available for the DMV11 Synchronous Controller beginning October 1, 1983.

~ Table E-4 DMV11 Option Configurations

OPTION CONFIGURATIONS

[

FACTORY INSTALLED OPTIONS
e DMV11-AP (System Option —
RS-232-C Version)

¢ DMV11-BP (System Option —
V.35 Version)

e DMV11-CP (System Option —
Integral Modem Version)

(

« DMV11-FP (System Option —

RS-423-A/449 Version)

FIELD UPGRADE OPTIONS

e« DMV11-M (Base Option)
|ele

e DMV11-N (Base Option)
For RS-232-C applications, one
of the following cabinet kits
must also be obtained with the
DMYV11-M Base Option:

\
R

_ CK-DMV11-AA
- CK-DMV11-AB

_ CK-DMV11-AC

For V.35 applications, one of
the following cabinet kits must

o
|

also be obtained with the
DMV11-M Base Option:

- CK-DMV11-BA

_ CK-DMV11-BB

[o]

- CK-DMV11-BC
e

Equipment supplied with option.

E-5

TK-11341

Table E-4

OPTION CONFIGURATIONS

DMYV11 Option Configurations (Cont)

(Cont)

For Integral Modem applications,
one of the following cabinet kits
must also be obtained with the
DMV11-N Base Option:

- CK-DMV11-CA
- CK-DMV11-CB

— CK-DMV11-CC
For RS-423-A/449 applications,
one of the following cabinet kits
must also be obtained with the
DMV11-M Base Option:
— CK-DMV11-FA

— CK-DMV11-FB
— CK-DMV11-FC

e Equipment supplied with option.
TK-11340

£n

E-6

QMA DMV11 Synchronous Controller

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