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AA-D319A-TA

December 1978

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Document:	Device Extensions User’s Guide
Order Number:	AA-D319A-TA
Revision:
Pages:	49
Original Filename:	http://bitsavers.org/pdf/dec/pdp8/os8/AA-D319A-TA_os8DevExt.pdf

OCR Text

,~D~DDmD

08/8
Device Extensions
User's Guide
Order No. AA-D319A-TA

OS/8
Device Extensions
User's Guide
Order No. AA-D319A-TA

ABSTRACT
This document describes the software support for the KT8A
Memory Management Option and the RX02 and RL01 devices.

SUPERSESSION/UPDATE INFORMATION:

This manual is an update of sections of the
05/8 Handbook (DEC-S8-0SHBA-A-D).

OPERATING SYSTEM AND VERSION:

05/8 V3D

To order additional copies of this document, contact the Software Distribution
Center, Digital Equipment Corporation, Maynard, Massachusetts 01764

digital equipment corporation · maynard, massachusetts

First Printing, December 1978

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.
The software described in this document is furnished under a license
and may only be used or copied in accordance with the terms of such
license.
No responsibility is assumed for the use or reliability of software on
equipment that is not supplied by DtGITAL or its affiliated companies.

The postage-prepaid READER'S COMMENTS form on the last page of this
document requests the user's critical evaluation to assist us in preparing future documentation.
The following are trademarks of Digital Equipment Corporation:

DIGITAL
DEC
PDP
DECUS
UNIBUS
COMPUTER LABS
COMTEX
DDT
DECCOMM
ASSIST-11
VAX
DECnet

DECsystem-10
DECtape
DIBOL
EDUSYSTEM
FLIP CHIP
FOCAL
INDAC
LAB-8
DECSYSTEM-20
RTS-8
VMS
IAS

MASSBUS
OMNIBUS
OS/8
PHA
RSTS
RSX
TYPESET-8
TYPESET-11
TMS-11
ITPS-10
SBI

CONTENTS

Page
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7

2.0
3.0
3.1
3.1.1
3.1.2
3.1.3

3.2
3.2.1
3.2.2
3.2.3
3.3

3.4
3.5
4.0
4.1
4.2
4.3
4.4

4.5
4.5.1
4.5.2
5.0
5.1
5.1.1
5.1.2
5.1.3
5.1.4
5.1.5
5.2
5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.4
5.4.1
5.5

INTRODUCTION AND OVERVIEW
Distribution Media
The RESORC Progr~
Changes in BASIC and FORTRAN IV for RL01 and
RX02 Users
System-Wide Changes for Users with the KT8A
Changes in PIP for RL01, RX02, and VXAO
The BOOT.SV Program
Changes in FUTIL
BOOTSTRAP AND BUILD INSTRUCTIONS
THE KT8A MEMORY MANAGEMENT OPTION
128K Monitor and CCL Commands -- SAVE, ODT, and
MEMORY
The SAVE Command
The ODT Command
The CCL Memory Command
128K PAL8
The FIELD Pseudo-Operator
Specifying Data and Instruction Fields -- CDF
and CIF
The ABSLDR
Determining Memory-Size at Run-Time
The VXAO Extended-Memory Device
The SAVECB Program
THE RX02 DUAL-DENSITY DISKETTE
RX02 Device Names
Formatting Diskettes for RX02
RX01 and RX02 Compatibility
Interleaving
Using RXCOPY with RX02
Formatting Diskettes with RXCOPY
RXCOPY Options
THE RL01 DISK
System Description
Disk Format
RL8A Controller Format
Instruction Set
OS/8 Data Space
Converting Block Numbers to Hardware Disk
Addresses
Handler Description
Loading and Bootstrap Procedure
Loading the RL01 Disk Pack
Booting from BOOT.SV
Booting from the Console Switches
ROM Bootstrap Switch Settings
Operating Instructions
Disk Formatting
System Building

iii

1
2
2
3
3
3
4
4
4
6

7
7
8
11
11

12
12
14
14
15
16
17
17

18
18
19
20
21
21
21
22

24
24
26
27
27
29

30
30
31

31
31
31

32
36

CONTENTS (Cont.)

Page
APPENDIX A

RX02 BOOTSTRAP PROGRAM

A-l

APPENDIX B

RLOl BOOTSTRAP PROGRAM

B-1
Index-l

INDEX

FIGURES
FIGURE

1
2

Memory-Size Subroutine
Devices A, B, C on RLOl Disk

15
22

TABLES
TABLE

1
2

3
4

5
6
7
8
9

Device Extensions Modules
RX02 Bootstrap
RLOl Bootstrap
l28K ODT Command Summary
Field Specifications for l28K MEMORY Command
RX01-RX02 Compatibility
OS/8 Single Density Diskette Interleave Scheme
OS/8 Double Density Diskette Interleave Scheme
RLOl Handler Information
RLFRMT Formatter Messages

1
4

5
9

11
18
19
20
29
33

1.0

INTRODUCTION ~ND OVERVIEW

The OS/8 V3D Device Extensions support the following new devices under
OS/8.
•
•
•

The KT8A Memory Management Option (limited support)
The RLOI Disk and Controller
The RX02 Double-Density Diskette and Controller

In addition, the Extensions package is a support release for RTS/8 V3
and MACREL/LINK Version 2, both of which can use the extended memory
provided by the KT8A. RTS/8 V3 also supports the RLOI and RX02.
The Extensions package is a superset of some OS/8 modules. It remains
completely compatible with OS/8 V3D and contains the modules listed in
Table 1.
Table 1
Device Extensions Modules
System Programs:
Name

New Version Number

Comment

OS8 MONITOR

system head,
capable
of
being run from the device,
supports
128K
words
of
memory

ABSLDR.SV

loads binary and image
into fields >7

PAL8.SV

13A

uses fields >7

CCL.SV

ceL
MEMORY
command
recognizes up to 128K words
available in system

PIP.SV

14A

works with RLOl, RX02, VXAO,
and new system head

RESORC.SV

includes
VXAO

BOOT.SV

includes primary bootstrap
for RLOl, RX02, and VXAO

RXCOPY.SV

double
formats single or
density
diskettes, copies
single
single density to
density and double density
to double density

FUTIL.SV

. recognizes new core control
block format for programs in
extended memory

RLOl,

RX02,

code

and

(continued on next page)

Table 1
(Cont.)
Device Upgrade Kit Modules
Patches:

(to be added with LOAD and SAVE commands)
New Version Number

Name

Comment.

BPAT.BN

Patch for BASIC

FPAT.BN

Patch for FORTRAN IV

Handlers:

(to be inserted with BUILD)

RLSY.BN

RLOl System Handler

RLO.BN

RLOI Non-system Handlers

RLI.BN
RL2.BN
RL3.BN
RLC.BN
VXSY.BN

VXAO System Handler

RXSYI.BN

RXOI System Handler

RXSY2.BN

RX02 System Handler

RXNS.BN

RXOI-RX02 Non-system Handler

This manual assumes that the user is familiar with the material in the
following documents:
OS/8 Handbook (DEC-S8-0SHBA-A-D)
OS/8 Handbook Update (DEC-S8-0SHBA-A-DN4)
OS/8 Software Support Manual (DEC-S8-0SSMB-A-D)
KT~A Memory Management Control User's Guide (EK-KT08A-UG-OOI)
RL~A Disk Controller Maintenance Manual (EK-RL8A-TM-OOI)

1.1

Distribution Media

The OS/8 Device Extensions are distributed on the following media&
RX02 diskette
RLOI disk
RK05 disk
TD8E DEC tape

1.2

The RESORC Program

The new RESORC program lists the system and non-system handlers for
the
RX02 and RLOI devices.
In addition,
it lists a special
handler -- called VXAO -- that enables you to use the extended memory
provided by the KT8A as though it were a separate device.
RESORC now has an overlay structure, enabling a user who buys
source program to enter information on user-written handlers.
2

the

1.3

Changes in BASIC and FORTRAN IV for RLOI and RX02 Users

RLOl and RX02 users must add the following patches to the BASIC and
FORTRAN IV run-time systems so that these programs recognize and
properly allocate space in memory for the second page of the system
handlers.
To patch the BASIC run-time system, enter the following commands.
~LOAD
~LOAD
~SAVE

SYS:BRTS.SV/I
dev:BPAT.BN
SYS:BRTS.SV

where
dev

is the distribution device

BPAT.BN

is the BASIC patch

To patch the FORTRAN IV run-time system, enter the following commands.
~LOAD
~LOAD
~

SAVE

SYS:FRTS.SV/I
dev:FPAT.BN
~:)Y8:

F/:nn. 8'J

where

1.4

dev

is the distribution device

FPAT.BN

is the FORTRAN IV patch

System-Wide Changes for Users with the KT8A

KT8A users must ensure that user-written programs and user-written
handlers do not contain the following combination of instruction
steps.
CIF
lOT
JMP I

/Change instruction field
/Any PDP8 lOT instruction
/The instruction that does the CIF

If you enable the KT8A and turn on the interrupts (for example, to run
OS/8 as a background task under RTS8), the KT8A hardware will return
to the wrong place on traps between the CIF and JMP I instructions.

1.5

Changes in PIP for RLOl, RX02, and VXAO

The ne~ version of PIP recognizes the RL01, RX02, and VXAO devices.
PIP sets the proper length for directories on the ZERO command and
determines whether it is
dealing
with
a
double-density
or
single-density diskette.
PIP also recognizes the new Monitor head. If you attempt to use the Y
option on the old version of PIP to move the new system head, PIP
responds with the error message
BAD SYSTEM HEAD

1.6

The BOOT.SV Program

The BOOT.SV program now includes a primary bootstrap for
and VXAO. The format is

RLOl,

RX02,

.BOOT dd
or
• BOOT
/dd
where
dd

1.7

is a legal OS/8 device specification, including RL, RX,
or vx.

Changes in FUTIL

The new version of the OS/8 file utility program FUTIL recognizes the
new Core Control Block format for user-programs in extended memory.
For a complete description of FUTIL, see the OS/8 Handbook Update.

2.0

BOOTSTRAP AND BUILD INSTRUCTIONS

Since the Extensions
bootstrap the RXOl,
system device.

package includes the system head, you can
RX02, RLOl, or RK05 distribution medium as a

Table 2 and Table
and
RLOl
device.
the
TD8E
DEC tape
Handbook.

The
are

bootstraps for
the
RX02
contain
the
PJ(05
disk
and
bootstraps
for
the
the OS/8
included
Chapter 1 of
in

The new handlers must be inserted into OS/8 with the BUILD program.
For information on adding handlers to OS/8, see the BUILD chapter in
the OS/8 Handbook.
NOTE
The console instructions in Tables 2 and
3 describe a PDP8-A.
For other PDP8
computers, see the OS/8 Handbook.
Table 2
RX02 Bootstrap
1.

Press in order the MD and DISP buttons to display memory
in the octal readout.

Press in order 0 and LXA to select memory field O.

Press in order 20 and LA
location 20.

start

instructions

data

(continued on next page)

Table 2
(Cont.)
RX02 Bootstrap
4.

Deposit the following octal
with D NEXT.
00020
00021
00022
00023
.00024
00025
00026
00027
00030
00031
00032
00033
00034
00035
00036
00037
00040
00041
00042
00043
00044
00045
00046
00047
00050
00051
. 00052
00053
00054
UU055
00056
00057
00U60
00061

values,

terminating

each

value

1061
1046
0060
3061
7327
1061
6751
7301
4053
4053
7004
6755
5054
6754
7450
5020
1061
6751
1061
0046
1032
3060
0360
4U53
3002
205U
5047
0000
6753
5U33
6752
5453
0420
0020

After you have deposited all the values, press 0033 and LA
start the program at location 33.

To start the bootstrap program, press INIT and RUN.

Table 3
RLOI Bootstrap
1.

Press in order the MD and DISP buttons to display memory
in the octal readout.

Press, in order, 0 and LXA to select memory field O.

Press, in order, 1 and LA to
address 1.

start

instructions

data

(continued on next page)

Table 3
(Cont.)
RLOI Bootstrap
4.

Deposit the octal values given
with 0 NEXT.
Address

Contents

00001
00002
00003
00004
00005
00006
00007
00010
00011
00012
00013
00014
00015
00016
00017
00020
00021
00022
00023
00024
00025
00026
00027
00030
00031
00032
00033
00034
00035

6600
7201
4027
1004
4027
6615
7002
7012
6615
0025
7004
6603
7325
4027
7332
6605
1026
6607
7327
4027
0377
7600
0000
6604
6601
5031
6617
5427
5001

below,

following

each

value

After all values are deposited, press, in order, 0001 and LA
to allow the program to start at location 1.

Press, in order, IN IT and RUN to start the bootstrap program.

The complete RX02 and RLOI bootstrap programs are listed in Appendix A
and B.

3 ,.0

THE KT8A MEMORY MANAGEMENT OPTION

The OS/8 V3D Device Extensions provide limited support for the KT8A
Memory Extension and Management Option, which increases the amount of
allowable memory in PDP8 systems from 32K to a maximum of 128K words.
The KT8A supports all available sizes of continuous memory from 32K to
l28K.
System programs, devices, and languages that run in 32K under OS/8
will also operate with the new monitor.
In addition, systems with the
KT8A and l28K software support will run user-written programs in
memory fields 0 to 37. OS/8 high-level languages and system programs,
however, do not make use of memory greater than 32K words.

This section describes the OS/8 commands and PAL8 instructions that
allow you to run user-written programs in fields 0 through 37. In
addition, it includes a subroutine for finding the amount of memory
available at run-time and describes a program that enables you to
ch~nge the Core Control Block of a program in complex SAVE operations.
This section also notes current software restrictions on
the extended memory.

the

use

For a description of the KT8A device, including operating and
programming instructions, see the ~K~T~8~A~~M~e~m_o~r~y~_M~a~n~a~g~e~m~e~n~t~C~0~n~t~r~o~l
User's Guide (EK-KT08A-UG-OOl).

3.1

128K Monitor and CCL Commands -- SAVE, ODT, and MEMORY

The SAVE and ODT monitor commands now support fields 0 to 37. The CCL
MEMORY command finds the highest field available in hardware up to
field 37. MEMORY also limits the available fields in software, but
this feature is currently restricted to 32K.
NOTE
The OS/8 Monitor currently requires that
all user-written programs contain at
least one segment (I-page minimum) below
32K.

3.1.1 The SAVE Command - The SAVE command makes a memory-image file
of the program currently in memory, assigns it a name, and saves it on
a device. You can specify areas in memory that you want to save in
fields from 0 to 37.
The format of the command, including all optional arguments, is
SAVE device:file.ex ffnnnn-ffmmmm,ffpppp;ffssss=cccc
where
ffnnnn

is a 6-digit octal number representing a field from 0
to 37 (ff) and the first address of a continuous
portion of memory you want to save.

ffmmmm

is the final address (in the same field) of the section
of memory you want to save.

ffpppp

is a 6-digit octal number representing the field and
address of one location in memory. If you specify a
single address on an even-numbered page in the command,
SAVE writes the entire page on which the location
occurs. If you specify an odd-numbered page, SAVE also
saves the preceding page.

;ffssss

is a 6-digit octal number representing the field
starting address of the program you are saving.

and

=cccc

is a 4-digit octal number representing the contents
the Job Status Word for the program.
(See below.)

If you omit the extension on the file name, SAVE appends .SV. If you
omit the other arguments, SAVE finds the locations it requires in the
current Core Control Block.
(For a discussion of the Core Control
Block, see the OS/8 Handbook and the OS/8 Software Support Manual.)
The SAVE command places the following restriction on arguments in
command line.
•

You must specify the output device.
DSK.

•

The first and last location of a
segment
in
memory
(ffnnnn-ffmmmm)
that you wish to SAVE must both exist in the
same field. You may not cross field boundaries.
In the
following example, both entries specify field 22.
~SAVE

•

SAVE does not default

the
to

SYS:EXAMPL 220055-220643

When you specify an area on a page, SAVE takes the entire
page.
If you call for another part of that page in the same
command line, SAVE sends a BAD ARGS error message to the
terminal informing you that it has already saved the page.
~SAVE

RXA1:FLOP 120077-120122, 120146-120177

The first argument writes locations 77 to 122 in field 12 on
to RXAI and calls the file FLOP.SV. The second argument,
which specifies locations on the same page, produces the error
message
BAD ARGS
•

Do not SAVE locations 7600-7777 in fields 0, 1, and 2.
The
resident Monitor code resides in these areas of memory. To
avoid accidently destroying a portion of the Monitor, restrict
SAVE operations involving 7600 to fields above 2.

you specify an address on an odd-numbered page, SAVE can
• If
save it only if it also saves the preceding page. The system
does this automatically.
If you wish to specify more locations in a SAVE command than you can
fit in a single command line, use the SAVECB program described in
Section 3.5.
NOTE
The Monitor START command
currently
accepts
field specifications in the
range of 0 to 7 only.

3.1.2 The ODT Command - aDT accepts and returns 6-digit addresses
the following commands.
ffnnnn/
ffnnnnB
ffnnnnG
where
ff
nnnn

is a field from 0 to 37
is a location
8

The 0 and F command allow you to specify fields in the range of 0 to
37.
To indicate the first eight fields, type a single octal digit
(0-7). Note that this is a change from previous versions of ODT,
which required you to enter field specifications as multiples of 10
(for example, field 2 as 20). Table 4 summarizes all of the OS/8 128K
ODT commands. For complete information on ODT, see the chapter on the
ODT program in the OS/8 Handbook.
Table 4
128K ODT Command Summary
Command
ffnnnn/

Operation
Open location ffnnnn, where ff is a field from 0
to
37.
ODT displays the contents of the
location, prints a space, and waits for you to
enter a new value for the location or close the
location. If you omit ff, ODT assumes field O.
Reopen the most recently opened location.

nnnn;

Deposit nnnn in the currently opened location,
close the location, and open the next location
in the sequence for modification. The semicolon
(;) lets you deposit a series of octal values in
sequential locations. To skip locations in the
sequence, type a semicolon for each location you
wish to leave unchanged.

RETURN key

CloSe the currently open location.

LINE FEED key

Close the currently open location, open the next
location in the sequence for modification, and
display its contents.

Open the current location plus n and display the
contents.

Open the current location minus
the contents.

uparrow or
circumflex

Close the location, read its contents as a
memory-reference instruction
and
open
the
location it points to, displaying its contents.

and

display

•

ODT
makes
no
distinction
between
instruction op-codes when you use this
command.
It treats all op-codes as
memory-reference instructions.

•

Take care when you use this command with
indirectly
referenced
auto-index
registers. If you use the command in
this way, the contents of the auto-index
register is incremented by one.
Check
to see that the register contains the
proper value before proceeding.
(continuea on next page)

Table 4
(Cont.)
128K ODT Command Summary
Command

Operation

(underline)

Close the current location, read the contents as
a twelve-bit address, and open that location for
modification, displaying its contents.

ffnnnnB

Establish a breakpoint at location ffnnnn, where
ff indicates a field from 0 to 37. ODT permits
only one breakpoint at a time.

ffnnnnG

Transfer control of the program
ffnnnn,
where
the
first two
represent a memory field.

Remove the breakpoint, if one exists.

Open for modification the location in which ODT
stored the contents of the accumulator when it
encountered the breakpoint.

Open for modification the location in which ODT
stored
the
contents of the Link when it
encountered the last breakpoint.

Open the Search Mask location, initially set to
7777.
To change the Search Mask, type a new
value into the location.

M <LF>

Open the lower search-limit location.
Type in
the location
(four octal digits)
where the
search will terminate.

M <LF><LF>

Open the upper search-limit location.
Type in
the location
(four octal digits)
where the
search will terminate.

nnnnW

Search the portion of memory defined by the
upper and lower limits for the octal value nnnn.
The search must be restricted to a single memory
field.
See the F command.

Open for modification the location containing
the data field (0 to 37) that was in effect at
the last breakpoint. To change the field, enter
a number from 0 to 37.

Open for modification the word containing the
field
(0 to 37)
used by ODT in the last W or
uparrow command (search or indirect addressing)
or in the last breakpoint, depending on which
occurred most
recently.
To
modify
this
location, enter a number from 0 to 37.

CTRL/O

Interrupt a lengthy search
the next COT command.

DELETE key

Cancel a number previously typed, up to the
last non-numeric character entered. COT responds
with a question mark, after which you enter the
correct location.
10

output

to location
digits
(ff)

and wait for

3.1.3 The CCL Memory Command - The MEMORY command finds the highest
field available in hardware up to field 37. rt also limits the
available fields in software, but this feature is currently restricted
to 32K words.
The format of the command is
MEMORY
or
MEMORY nn
where
nn

is an octal number in the range of 0 to 37 representing
the number of 4K fields available to OS/8.

Table 5 lists all the values of n (memory fields
corresponding memory-size.

octal)

and

the

Table 5
Field Specifications for l28K MEMORY Command
n

Words of Memory

0
1
2
3
4
5
6
7

all available memory
8K
12K
16K
20K
24K
28K
32K

To limit memory, enter the highest file you want to make available to
OS/8 in the command line. For example, the following command limits
the available memory to 16K words.
~MEM

To find the amount of memory that OS/8 is using, type the command with
no argument.
~MEMORY

12K OF 32K MEMORY
In this example, MEMORY prints the information that a 32K
been limited to 12K words.

system

has

MEMORY caused the execution of the CCL.SV program.

3.2

128K PAL8

The following PAL8 instructions accept field specifications in the
range of 0 to 37, permitting you to run programs in areas above 32K.

3.2.1 The FIELD Pseudo-Operator - The pseudo-op FIELD instructs PAL8
to output a field setting so that it can recognize more than one
memory field.
The format of this pseudo-op is
FIELD ff
where
ff

is an integer, a previously defined
expression in the range 0 to 37.

symbol,

FIELD causes the PALS assembler to output a field setting from 0 to 37
during the second pass of assembly. This setting, which appears as
the high-order bits of the location counter in the program listing,
tells the ABSLDR which field to load information into.
For example, the following FIELD pseudo-op specifies memory field 26.
The next line sets the location counter to begin at 400. Note that
the FIELD instruction must precede the starting location.
ICORRECT EXAMPLE

FIELD 26
*400

The following example is incorrect and will not generate the code
want.

you

IINCORRECT EXAMPLE

*400

FIELD 26

3.2.2 Specifying Data and Instruction Fields -- eDF and elF - The CDF
and CIF instructions let you specify field 0 to 37 as data and
instruction fields.
Entering the argument requires knowledge of the
bit arrangement of these two instructions.
CDF

6201

A CDE B
110 010 000 001

CIF

6202

110 010 000 010

Bits A CDE B indicate the data or instruction field that the program
will jump to at the next indirect JMP or JMS.
(The positioning of
ABCDE is eccentric as ACDEB maintains compatibility between KT8A and
existing 32K systems.)
To specify a field from 0 to 7, you use bits CDE only.
the instruction is

The format

CDF or CIF nO
where
nO

is an octal number that PAL8 ORs with
code

is an octal digit from 0 to 7 (bits CDE)

the

instruction

For example, this instruction
CIIF

specifies field 6 by causing PAL8
Instruction code
Argument

do the following OR.

6201
60

A CDE B
110 010 000 001
000 000 110 000

6261

110 010 110 001

To specify a field from 10 to 17, use bits COE and
format of the instruction is

set

bit

The

COF or CIF n4

is an octal number that PAL8 ORs with
code

is an octal value from a to 7 (bits COE)

is an octal value indicating a field range of 10 to
(sets bi t B)

the

instruction

For example, this instruction
C[lF 64

indicates field 16.
Keep in mind that to call for fields above field 7 (above 32K) with
COF and CIF, you must first load the KT8A Extended Mode Register with
the LXM instruction. For example, the following code deposits (7777
in field 12, location 10000

LXH
C[lF 24
TAIl (7777
IICA I (1000

To specify a field from 20 to 27, use bits COE and
format is

set

bit

The

COF or CIF InO
where
InO
1

is an octal number that PAL8 ORs with the instruction
is an octal value indicating field range 20 to 27 (sets
A)

is a value from 0 to 7 (bits COE)

For example, this instruction
C[lF 160

indicates field 26.

To specify a field from 30 to 37, use bits CDE and set bit
The format is

and

CDF or CIF In4
where
In4

is an octal number that PAL8 ORs with the instruction

1 ••• 4

are octal values indicating a field range of 30
(set bits A and B)

is an octal digit in the range 0 to 7 (bits CDE)

For example, this instruction
C[lF 164

specifies field 36
One way to avoid confusion with this unusual bit configuration
define high fields with convenient mnemonics. For example:
F36=164
C[lF F36

3.2.3 The ABSLDR - The ABSLDR will load information into any field
from 0 to 37 that you specify in the FIELD pseudo-oPe However, the
ABSLDR option In is restricted to fields 0 to 7 only.
The =ffnnnn option sets the starting address of the program in memory
to ffnnnn, where ff is a field from 0 to 37 and nnnn is a location.
If you omit the option or specify 0, the ABSLDR inserts a starting
address of 0200 in field o.

3.3

Determining Memory-Size at Run-Time

It is frequently helpful to know the amount of memory currently
available to the program you are running.. The sub-routine in Figure 1
determines the amount of memory available in a 128K system at
run-time.
The program returns a value in the range of 0 to 40 to
indicate the first non-existent field in the system.
To use this routine above 32K, you must first load the Extended Mode
Register with the LXM instruction. For complete information on the
Extended Mode Register, see the KT8A Memory Management Control User's
Guide.

/SUBROUTINE TO DETERMINE MEMORY SIZE

PAL8-VI0A 04-AUG-78

/SUBROUTINE TO DETERMINE MEMORY SIZE
/THIS SUBROUTINE WORKS ON ANY PDP-8 FAMILY
/COMPUTER. THE VALUE, FROM 1 TO 40 OCTAL,
/OF THE FIRST NON-EXISTENT MEMORY FIELD IS
/RETURNED IN THE AC.
/NOTE -- THIS ROUTINE MUST BE PLACED IN FIELD 0
UU2UO
00201
00202
00203
00204
00205
OU206
002U7
U0210
00211
00212
00213
00214
00215
00216
00217
00220
00221
00222
OU223
00224
00225
00226
00227
OU230
00231
00232
Ou233
UU234
OU235
00230
OU237
UU24U
U0241
UlI242
uU243

0000
73UO
6201
1242
lI222
7112
7012
7002
7430
1243
0235
3214
6201
164U
7000
3214
1216
3640
0037
1640
7400
1224
1241
7640
5235
1214
364CJ
2242
52U2
6201
1242
560U
0224
14(JU
lIUUl
00U4

CORE,

CLA CLL
CORO,
CDF 0
TAD
CORSIZ
AND
COR37
CLL RTR
RTR
BSW
SZL
TAD
C4
AND
COREX
DCA
.+1
CORl,
CDF
TAD I
CORLOC
COR2,
NOP
DCA
CORI
TAD
COR2
DCA I
CORLOC
COR37,
37
TAD I
CORLOC
CORX,
7400
TAD
CORX
CORV
TAD
SZA CLA
JMP
COREX
TAD
CORI
DCA I
CORLOC
ISZ
CORSIZ
JMP
CORO
COREX, CDF
TAD
CORSIZ
JMP I
CORE
CORLOC, CORX
140u
CORV,
CORSIZ, 1
C4,
4

Figure I

3.4

/(NEEDED FOR PDP-8L)
/GET FIELD TO TEST
/MASK USEFUL BITS
/TRANSFORMS
/"37" TO "174"
/FOR CDF

/SET UP CDF TO FIELD
/CDF IS PROCESSED HERE
/SAVE CURRENT CONTENTS
/(HACK FOR PDP-8!)
/7000 IS A "GOOD" PATTERN

/(HACK FOR PDP-8.,NO-OP)
/TRY TO READ BACK 7000
/(HACK FOR PDP-8.,NO-OP)
/GUARD AGAINST "WRAP-AROUND"
/TAD (1400)
/NON-EXISTENT FIELD EXIT
/RESTORE CONTENTS DESTROYED
/TRY NEXT HIGHER FIELD
/LEAVE WITH DATA FIELD 0
/lST NON-EXISTENT FIELD
/ADDRESS TO TEST IN EACH FIELD
/7UUO+74UO+1400=0
/CURRENT FIELD TO TEST

Memory-Size Subroutine

The VXAO Extended-Memory Device

The VXAO device handler enables you to use the extended memory
provided by the KT8A as though it were a separate device. You call
VXAO in the same way that you call any system device.
For example,
this command
~COpy

VXAO:SAMPLE<RXAO:SAMPLE

copies a program called SAMPLE into an area of memory above 32K words.
The VXAO device provides high speed I/O for users with diskettes or
users who want the performance of a fixed-head disk type of storage
device.

3.5

The SAVECB Program

SAVECB is a demonstration program that enables you to alter the
contents of a program's Core Control Block.
You will find this
routine useful in a SAVE with arguments involving more fields in
memory than you can specify in a single SAVE command line. This is
likely to happen in systems with 128K words of memory, since the
number of fields you may wish to specify increases from 10 to 40
(octal) .
The format for summoning SAVECB is
R SAVECB
* file.SV
where
file.SV

is the name of
change

program

whose

CCB

you

want

SAVECB responds with a number sign (#) to indicate that it is ready to
accept one of the following commands.
TYPE

displays core control block of file.SV

Affmmmm-ffnnnn

adds segment to CCB

Sffmmmm-ffnnnn

subtracts segment from CCB

To exit from the program, type

This writes the updated Core Control Block onto the system area of the
device.
In order to change the program's CCB, you must load the
program with the R command (typing CTRL/C to abort execution) and then
create a memory-image file with SAVE.
For example, assume you want to save segments of program FLOP.SV as a
memory-image file called FLAP.SV.
First, you modify the CCB with
SAVECB.

!R SAVECB
FLOf'.SV

SAVECB responds with a number sign (#).
program, type

To inspect the

CCB

your

!TYF'E
SAVECB displays the starting location of the program, its
Word, and the segments in memory that it uses.

START=OOOO

Job

JSW::::2000

CORE SEGMENTS:
040200-040377,020200-020377,016400-017377,000000-007577

To add segments to the CCB, enter them after the prompt.
!A30200-30600,40600-40777

Status

Now examine the CCB again.
tTYPE
START=000200

JSW=2000

CORE SEGMENTS:
040200-040377¥040600-040777~030200-030600~020200-020377

016400-017377,000000-007577

To place this core control block in the system
type @ after the prompt.

area

the

device,

To make a memory-image file of the segments specified in the CCB run
FLOP.SV with the R command aborting execution with CTRL/C. Then save
the segments under the new name with a SAVE command without arguments.
~R

FLOP.SV

~SAVE

FLAP.SV

To change a segment, first subtract the entire segment with
command. Then enter the altered version with the A command.

4.0

the

THE RX02 DUAL-DENSITY DISKETTE

The OS/8 V3D Device Extensions include system and non-system handlers
for RXOI and RX02, the devices for single-density and double-density
diskettes. The new handlers run on both RXOI and RX02 hardware.
NOTE

4.1

•

The old OS/8 handlers,
including
BOOT/RX, will not run on RX02.

•

An
RX02
with
hardware switch
an RXOI.

a
single-density
set is identical to

RX02 Device Names

To specify an RX02 diskette in an OS/8 command line, enter
device names you use for RXOI.
OS/8 recognizes the
permanent names.
DSK

Default output device, usually same as SYS

SYS

System device, usually the diskette in drive 0

RXAO

The diskette in drive 0

RXAI

The diskette in drive 1

the same
following

SYS is most accurately defined as the device that
you
have
bootstrapped.
This is usually the device in drive O.
However, the
hardware will also bootstrap a device in drive 1, making SYS and DSK
equivalent to RXAI.
The permanent names RXAO and RXAI
remain
unchanged.

4.2

Formatting Diskettes for RX02

Diskettes arrive from the factory already formatted
for
use in a
single-density RXOI drive.
To format them for RX02, use the RXCOPY
program with the /0 option,
specifying the diskette you want to
re-format as an output device.
(If you enter a device by itself in
the command line, RXCOPY considers it to be an output device.)
Diskettes formatted for the RX02 device contain
the directory) in a l2-bit mode.

4.3

981

blocks

(besides

RXOI and RX02 Compatibility
diskette runs
Similarly,
a

only on an
RX02
single-density SYS

•

A double-density system
double-density
drive.
requires an Rxul drive.

•

RX02 accepts both single-density and double-density non-system
diskettes.
The non-system handler determines which kind of
device it is dealing with and proceeds accordingly.

•

RXOI
hardware
accepts
single-density use.

only

diskettes

formatted

for

NOTE
If you place an RX02 diskette on an RXOI
drive, you can currently write to it
without producing an error
message.
Avoid this procedure, as it results in a
"mixed" diskett.e.
Table 6 matches single-density and double-density diskettes -- both
system and non-system -- with the drives that they run on.
Table 6
RXOI-RX02 Compatibility
r-----

Diskette Type

Drive type
Single density

Single-density System

Double-density System
Single-density Non-system

Double density

X
X

Double-density Non-system

X
X

4.4

Interleaving

OS/8 writes blocks on single-density diskettes with an interleave of
2.
This means that it skips a block between each block that it reads
or writes. with double-density diskettes, ~OS/8 uses an interleave
scheme of 3, skipping two blocks. Tables 7 and 8 show the interleave
schemes for both sing1e- and double-density diskettes.
Table 7
OS/8 Single Density Diskette Interleave Scheme
OS/8 Logical Block (octal)

Diskette Sectors (track/sector--decima1)

1/1

1/3

1/5

1/7

1/9

1/11

1/13

1/15

1/17

1/19

1/21

1/23

1/25

1/2

1/4

1/6

1/8

1/10

1/12

1/14

1/16

1/18

1/20

1/22

1/24

1/26

2/1

2/3

2/5

2/7

2/9

2/11

2/13

2/15

2/17

2/19

2/21

2/23

2/25

2/2

2/4

2/6

2/8

2/10

2/12

2/14

2/16

2/18

2/20

2/22

2/24

2/26

3/1

3/3

3/5

3/7

·
·
·

Table 8
OS/8 Double Density Diskette Interleave Scheme
OS/8 Logical Block (octal)

Diskette Sectors (Track/sector--decimal)

1/1

1/4

1/7

1/10

1/13

1/15

1/19

1/22

1/25

1/2

1/5

1/8

1/11

1/14

1/17

1/20

1/23

1/26

1/3

1/6

1/9

1/12

1/15

1/18

1/21

1/24

2/1

2/4

·
·
·
OS/8 does not use Track 0, and you cannot
mode.

4 ..5

access

the

l2-bit

Using RXCOPY with RX02

RXCOPY copies both single-density and double-density diskettes on RX02
drives.
If the output diskette does not match the input diskette,
RXCOPY will re-format it to the proper density.
In default mode, RXCOPY compares the two diskettes for identical
contents before it makes a copy. For a quicker transfer, use the /N
option, which inhibits the comparison.
For double-density transfers involving a comparison of contents,
RXCOPY will use 16K words of memory if it is available on the system
for faster operation. If possible, use the MEMORY command to provide
the necessary memory.

4.5.1 Formatting Diskettes with RXCOPY - RXCOPY with the /S and /0
option formats diskettes for single-density or double-density use. To
format a diskette, enter it by itself in the command line, followed by
the option.
(RXCOPY considers a device entered by itself to be an
output device.)
For example, the following command sequence re-formats the diskette in
drive 1 from single-density to double-density.
~R

RXCOPY

~RXA1:/D

To change it back to single-density, type
~R

RXCOPY

~RXA1:/S

4.5.2

5.0

RXCOPY Options - RXeOPY provides the following options.

•

RXCOPY pauses and waits for user response
after transfers. To continue, type Y.

•

RXeOPY transfers the contents of one diskette to
but does not check for identical contents.

•

RXCOPY checks both diskettes for identical contents and
lists the areas that do not match but performs no
transfer.

•

RXCOPY reads every block on the input
bad sectors but performs no transfer.

•

RXeOPY formats the diskette specified as an output device
to single-density.

•

RXCOPY formats the
double-density.

•

This option is equivalent to default copy and match.

device

before

and

another

and

lists

RXeOPY prints its current version number.

diskette

specified

for

output

THE RLOI DISK

This section describes "the booting, formatting and building of the
RLOl disk pack with the OS/8 Operating System, using the RLOl OS/8
software support package.
The RLOl disk pack -- a high-density mass storage device ~- utilizes
bad-block mapping.
Bad blocks occur during the manufacture of disks
or develop as a result of use and age. Bad block~ that are present
after manufacture are recorded in factory-written lists. Each disk
preserves its own individual list.
The RLFRMT formatter program
detects and lists new bad blocks that occur during disk operation in
the field.
Each RLOl disk main~ains up to 45 bad blocks;
this allows
the life of the disk to oe prolonged as a mass storage device.
The RLOl requires a PDP-8A,E,F or M with at least 12K of memory.
Non-omnibus PDP-8 family computers are not hardware-compatible with
the RL01.

System

and

non-system RLOI handlers are standard two-page OS/8
Two-page handlers require 12K of memory because the second
page of the handler resides in the last page of field 2.

handlers~

BATCH may be run using RLOI disks, even on a system with 12K words
memory. However, disk formatting cannot be done under BATCH.

This section inc1udes a system description, detailing disk, RL8A
controller and software formats. In addition, it contains bootstrap
procedures and
operating
instructions,
including
a
detailed
presentation of messages that are generated during disk formatting.

5.1

System Description

The RLOI disk pack has three logical "devices" that are designated as
Device A, Device B and Device C. Figure 2-1 shows device designation
on an RLOI disk.
The OS/8 Device Extensions provide for the standard OS/8 System and
Non-System I/O transfer of 1 to 32 (decimal) memory pages to or from
anyone of three RLOI "devices". The "devices" are located on anyone
of four RLOI disk drives.
Disk data-space consists of 777 (octal) tracks. As shown in Figure 2,
data on a single track is made up of 40 equal length sectors numbered
o through 47 (octal). This results in 20 (decimal) blocks, four
assigned to Device C and 16 to Device A or B.
DISK DATA SPACE

•

(TRACK 0

(TRACK 777

EVEN SECTORS
ONE RL01 T RACK {

16 20

ODD SECTORS
461

4 BLOCKS

16 BLOCKS

AOR B

--47

Track and Sector numbers are octal
Block numbers are decimal

Figure 2

Devices A, B, C on RLOI Disk

Approximately 10,000 (decimal) OS/8 blocks are supported per drive,
40% as Device A, 40% as Device B, and 20% as Device C.
This scheme
provides some user control over the tradeoff between the number of
devices and the length of each device.
Device C has a different length from Devices A and B.
In general,
Device C is used only when a maximum amount of data is to be stored on
the disk.

Each device supports up to 15
(decimal)
bad blocks to provide
bad-block mapping.
These blocks may be thought of as "spares", and
should never be accessed by the user.
This support
involves
"invisible" mapping of OS/8 block numbers into the set of actual good
disk blocks; no utility program need be changed (including SQUISH),
and user awareness of this feature is not required. Bad-block lists
are kept resident to reduce the extra reads required.
Bad-block lists that occur during disk manufacture are maintained in
factory-generated lists which are stored on track 777 of the disk.
The OS/8 system preserves five copies of the factory list, all of
which are identical.
When a disk is initially formatted using OS/8, the formatting program
(RLFRMT)
ascertains that the disk is new. The program then reads in
the factory list, and checks the disk for any new bad blocks.
The
factory list and the new bad-block list are then combined, and, after
the user's go-ahead, the formatting program writes the newly-generated
OS/8 bad-block list on track 0 of the disk.
When running OS/8, you may generate an I/O error because of a bad
block.
You can check this by again running the formatter program.
RLFRMT ascertains that the disk is already formatted, so it reads in
the previous OS/8 bad-block list and checks the disk for any new bad
blocks. When you instruct it to proceed, the formatting program
writes the updated OS/8 bad-block list on track 0 of the disk. You
should not allow the bad block list to be written if an unexpectedly
large number of bad blocks are reported~
formatting to remove bad
blocks is a permanent, irreversible procedure.
During an I/O transfer, the handler first reads in the OS/8 bad-block
list for the device.
The system effectively maps around the bad
blocks.
This has the effect of making them appear
to
have
disappeared, so that standard OS/8 block numbers can be used.
All permanent information stored on RLOI disk packs (such as bad-block
lists)
is protected from destruction by OS/8 handler calls by being
"outside of" the OS/8 data space.
An annulus data scheme reduces the average intra-device seek time.
This means that data continues from the track on surface 0 to the
track on surface I for each cylinder.
The bootstrap routine is under 32
(decimal) words in
suitable for ROM implementation and/or direct toggle-in.
Three tries (two
reported.

retries)

are

attempted

before

numbers

NOTE
Unless otherwise noted, all
this section are octal.

length,
I/O

error

and
is

5.1.1

Disk Format - The format of the RLOI disk is as follows:

Track

Sector

Contents

0
U
U

0
2
4
6
10
12
14
16
20
22

Reserved for future use by DIGITAL
Reserved for future use by DIGITAL
Reserved for future use by DIGITAL
Reserved for future use by DIGITAL
Reserved for future use by DIGITAL
Reserved for future use by DIGITAL
Bad Block Lists for Devices A and B
Bad Block List for Device C
Device A, Block 0 (first half)
Device A, Block 0 (second hal f)

Device C, Block 0 (first half)
Device C, Block 0 (second half)

0
0
0

0
0
0
0

1
1

Device B, Block 0 (first half)
Device B, Block 0 (second half)

400
400

777

Disk Pack Serial Number, List
of Manufacturing-Detected Bad Sectors
and Field-Detected Bad Sectors.
NOTE

RLFRMT.PA contains complete descriptions
of bad block list formats as comments at
the start of the program.

5.1.2 RL8A Controller Format - The
software control of the system.

following

registers

perform

Memory Address Register:
The Memory Address Register is a l2-bit register that contains
location at which the first transfer is to be performed.

I I I I I I I I I I I IJ
-'Y

Memory address _ _ _ _

Memory Address Register

the

Word Count Register:
The Word Count Register is a l2-bit register that contains
negative of the number of words to be transferred at one time.
5

I I I

I I I I

'--

Word count

the

Word Count Register
Sector Address Register:
The Sector Address Register contains the
through 5.
5

........

address

bits

Sector address

sector

Sector Address Register
Command Register A:
Command Register A contains the direction,
address.
It has the following format:

surface

and

cylinder

Direction _ _ _- - I
0: towards lower cylinder
addresses (outside)
1: towards higher cylinder
addresses (inside)
Surface - - - - - - - '
0: upper surface
1: lower surface
Cylinder address - - - - - - - - - - - - - - - - - - '
(or cylinder difference)

Command Register A
Command Register B:
Command Register B designates maintenance mode, byte mode,
interrupt
enable, drive select, memory field and function.
It has the following
format.

Maintenance mode
Byte mode - - - - - - - - - '
0: truncated
1: byte
Interrupt enable - - - - - - - '
Drive select - - - - - - - . - - - - - - '
Memory field - - - - - - - - - - - - - - - - - - - '
Function -----------------------~
0: maintenance
1: reset drive errors
2: get drive status
3: seek
4: read next header
5: write
6: read
7: read, no header check

Command Register B
5.1.3 Instruction Set - The following instructions operate
system.

the

disk

Note that the AC is cleared after a transfer from the AC to a register
in the controller. Also,-the AC is cleared first before a transfer is
made from a controller register to the AC.
The skip instructions are skip and then clear rOT's;
that is,
if a
given condition
(function done) is true, the function-done flag will
be cleared at the completion of the skip rOT.
Function

Octal Code

Mnemonic

6600

RLDC

Clear device, all registers, AC and flags
not use to terminate a disk function)

6601

RLSD

Skip on function done flag, then clear it

6602

RLMA

Load memory address register from AC

6603

RLCA

Load command register "A" from AC

6604

RLCB

Load command reg ister
command

6605

RLSA

Load sector address register from AC bits 0-5

6606

liB II

from

AC,

execute

Spare (will clear the AC)

6607

RLWC

Load word count register from AC

6610

RRER

Read error register into AC bits 0-2 and 11

6611

RRWC

Read word count register into AC

6612

RRCA

Read command register

A" into AC

(do

Octal Code

Mnemonic

6613

RRCB

Read command register "B" into AC

6614

RRSA

Read sector address register into AC bits 0-5

6615

RRSI

Read (silo) word (8-bi t) into AC bits 4-11

Function

Spare (does not clear AC)

6616
6617

RLSE

Skip on composite error flag, then clear it

Devices

Addresses - Use

the

5.1.4 OS/8 Data Space - The layout of OS/8 data space on
B, and C is as follows:
Devices A and B
Block

Track

Sectors

0
1
2
3
4
5
6
7
10
11
12
13
14
15
16
17
20

0
0
0
1

20,22
24,26
30,32
34,36
40,42
44,46
1,3
5,7
11,13
15,17
21,23
25,27
31,33
35,37
41,43
45,47
20,22

Block

Track

Sectors

0
1
2
3
4

1
1
1
1
2

0,2
4,6
10,12
14,16
0,2

0
()

0
0
0
0

°0
0
0

Device C

5.1.5 Converting Block Numbers to Hardware Disk
following procedures.
For Devices A and B:

The sector address is 4 times the sector code minus 27.
address is negative, add 47.

If the sector

Device A has MSB of cylinder
Device B has MSB of cylinder

= 0 (cylinders 0-177).
= 1 (cylinders 200-377).

The block number software format for Devices A and B is shown
following diagram.

the

BLOCK NUMBER:
LSB OF CYLINDER

SECTOR
CODE

S
U
R

F
A
C
E

Block Number Format for Devices A and B
For Device C:
The sector address is 4 times the sector code. The track is one plus
the track code. Tracks 0 and 777 cannot be addressed: this ensures
the integrity of the factory-detected and OS/8 bad-block lists, which
reside on these tracks.
The block number software
following diagram.

format

for

Device

shown

the

~·~--~-T-RA~C--K-C~O-D-E~--~--~~-4~--~~
-C

BLOCK NUMBER:

SECTOR

CODE

Block Number Format for Device C
The track software format for Devices A, B, and
following diagram.

shown

o
TRACK:
CYLINDER ADDRESS

S
U

R
F
A
C
E

Track Format for Devices A, B, and C

the

5.2

Handler Description

The standard OS/8 device designation format cannot be used with the
RLOI.
Normally, the standard format would use "RLAO:
to represent
Device A of unit (drive) O. The single-word format used internally to
store device names does not distinguish between "RK" devices and "RL"
devices, resulting in erroneous RESORC reports, and
in
other
anomalies. The RLOI therefore uses "RLOA" to represent unit 0, Device
A, and so forth. Table 9 provides information on the RLOI handlers.
SYS is the same device as RLOA (Drive 0, Device A).
Table 9
RLOI Handler Information
Device
Name

Entry
Point
Offset
(Octal)

File
Name
(Group
Name)

Device
Type

Device
Code
(Octal)

Octal
Length
(Blocks)

Decimal
Length
(Blocks)

SYS
RLOA
RLOB
RLOC
RLIA
RLIB
RLIC
RL2A
RL2B
RL2C
RL3A
RL3B
RL3C

07
44
40
50
45
41
54
46
42
60
47
43
64

RLSY
RLO
RLO
RLC
RLI
RLI
RLC
RL2
RL2
RLC
RL3
RL3
RLC

RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI
RLOI

26
26
26
31
26
26
31
26
26
31
26
26
31

7761
7761
7761
3751
7761
7761
3751
7761
7761
3751
7761
7761
3751

4081
4081
4081
2025
4081
4081
2025
4081
4081
2025
4081
4081
2025

A brief description of RLOI handler operation is as follows:
1.

When initially called, each RLOI handler executes once-only
code to read in the bad block list for its drive. The
handler error return is taken (with AC=4000) if an I/O error
occurs or if the bad-block list is found to be invalid (a
valid bad-block list begins with a special identification
code) •

Get handler arguments.

Map each block to be transferred around bad blocks by
incrementing the block number once for each bad block (as
listed in the bad-block list for the requested device)
less
than or equal to the present block. This procedure makes bad
blocks effectively "disappear."

Transfer one page/sector at
number of pages.

If an I/O error occurs for any RLOI read or write operation,
retry twice then take the System or Non-System Handler error
return with AC=4000.

time,

the

requested

5.3

Loading and Bootstrap Procedure

The following sequence of operations occurs
the RLOI.

during

bootstrapping

BOOT-I, the primary bootstrap routine, is read into locations
00001-00035 from a ROM, from BOOT.SV, or toggled in through
the console switches. The starting address is 00001. BOOT-l
clears Drive 0 and reads and starts BOOT-2.
If an I/O error
occurs, BOOT-l will repeat until it is successful.

BOOT-2 occupies locations 00000-00177. BOOT-2 reads the OS/8
Resident Monitor into the last pages of fields 0, 1, and 2.
If an I/O error occurs, BOOT-2 will "hang" as an indication
of failure to boot.

BOOT-2 then calls the Keyboard Monitor by jumping to location
07605.
NOTE
Never replace the system disk
pack
without rebooting:
each pack has its
own OS/8 block numbering scheme that is
determined during formatting.

Replace non-system disk packs only after the Monitor dot appears on
the terminal. This is done to ensure that the bad-block list read by
the handler is correct.

5.3.1 Loading the RLOI Disk Pack - Prepare
loading as follows:
1.

RLOI

Disk

Separate the protective cover from the disk pack,
following steps.

Pack

for

using

the

Lift the cartridge by grasping the handle with the
hand.

Support the cartridge from underneath with the left hand.

Lower the handle and push the handle slide
with the thumb of the right hand.

the

left

Raise the handle to its upright position to separate
cartridge from the protection cover.

the

Place the cartridge in the drive shroud
recess facing the rear of the machine.

Rotate the
cartridge
a
few
degrees
clockwise
and
counter-clockwise to ensure that it is properly seated within
the shroud.

Gently lower the handle to a horizontal
the drive spindle.

Place the protection cover on top of the cartridge.

Carefully close the drive lid.

Push the "LOAD/RUN" pushbutton.
30

with

the

right

position

handle

engage

5.3.2 Booting from BOOT.SV - Boot from the BOOT.SV program
the BOOT or R commands as follows:

using

• BOOT
7RL
or
~BOOT

or
.R BOOT
/RL

5.3.3 Booting from the Console Switches - The following
enters the bootstrap program into PDP-8/A memory.
buttons

Press in order the MD and DISP
numbers are being deposited.

Press, in order, 0 and LXA to select memory field O.

Press, in order, 1 and LA to start
address 1.

instructions

Deposit the octal values given in
value with D NEXT.

Table

following

each

After all values are deposited, press, in order, 0001 and
to allow the program to start at location 1.

Press, in order, INIT and RUN to start the bootstrap program.

see

procedure
what

5.3.4 ROM Bootstrap Switch Settings - Set the bootstrap
settings for ROM's labeled 465A2 and 469A2 as follows:

octal

switch

Program

82-5

82-6

82-7

S2-8

Sl-l

81-2

Sl-3 Memory Address

RL8A

OFF

5.4

4000

Operating Instructions

You must format new RLOI disk packs by running the RLFRMT program
prior to any 08/8 use (including system building). This is required
because RLFRMT constructs and writes specially formatted bad-block
lists on the pack.
08/8 RLOI operations on disks that have not been formatted with RLFRMT
result in error reports. Therefore, you should run RLFRMT even before
using BUILD to build a new system head.
Device C non-system handlers are provided to access all available
storage capacity of the RLOI disk packs. Transfers to or from Device
C are slower than those to or from Devices A and B.
This is so
because, while Deviqe A and B use 80% of each track, Device Conly
uses 20% of each track (only 4 blocks are stored on each track).
Thus, the time spent in seeking new tracks will be higher for Device
C.

Because different RLOI packs may have different patterns of bad,
blocks,
it is good practice to end an OS/8 session with the monitor
"BOOT" command (or "R BOOT"), so that other users will be able to type
"RL" to boot their disks. Of course, this procedure is unnecessary if
the computer system has a hardware bootstrap for the RLOI.

5.4.1 Disk Formatting - Format all new RLOI disk packs prior to any
use under OS/8, including system building. Mount the RLOI disk pack
(Section 4.2).
Format the RLOI disk by using the following procedure:
1.

Type
.!oR RLFRMT

to run the formatter program.
RLFRMT Vvp is printed on the terminal signifying the start of
the operation where:
v is the version number
p is the patch level letter
the program then prompts with

DRIVE?
2.

Type the drive number

(0-3) on which the pack is mounted.

The formatter program then reads all blocks on the disk to
detect any new bad blocks.
The process takes 35 to 40
seconds. After this period, an initial display is presented
as follows:
UNFORMATTED (NEW) DISK PACK SERIAL NUMBER nnnnnnnnnn
FACTORY-DETECTED BAD BLOCKS: NONE
NEWLY-FOUND BAD BLOCKS: NONE
NEW OS/8 BAD BLOCKS: NONE
FORMAT PACK WITH THIS NEW LIST?
The messages are explained
Messages.
3.

Table

10,

RLFRMT

Formatter

Type a "Y" or "N" (followed by a RETurn) in response to the
last message "FORMAT PACK WITH THIS NEW LIST?" to either
allow or prevent the writing of the new OS/8 bad-block lists.
The
program signifies completion of this. operation by
displaying

DONE
DRIVE '~
Type CTRL/C to return to the OS/8 monitor.
or designate another drive for formatting.

Remove

the

pack

The following example illustrates possible messages that may
be generated during a particular sequence of OS/8 RLOI
formatting operations if bad blocks are found.
OS/8 (OLD) DISK.
WARNING: ALL FACTORY-WRITTEN LISTS DESTROYED.
PREVIOUS OS/8 BAD BLOCKS: NONE
NEWLY-FOUND BAD BLOCKS: A 6374
A 6375
B 4347
B 4350
C0514
C 0515
C 2073

0360

WARNING: AN ADDITIONAL BAD BLOCK FOUND.
ZERO DISK BEFORE USE!
NEW OS/8 BAD BLOCKS: A 6374
A 6375
B 0360
B 4347
B 4350
C 0514
C 0515
C 2073
FORMAT PACK WITH THIS NEW LIST?
The formatter program then writes or does not write special OS/8 bad
block lists on the pack, depending on a "Y" or "N" user response.
These lists include only the factory-detected and newly-detected bad
blocks for new packs, or previous OS/8 and newly-detected bad blocks
for old packs.
warnings are given for various conditions
as
appropriate (see Table 10).
NOTE
Reformatting a previously-used disk pack
will make any newly-detected bad blocks
effectively disappear from the pack.
Any files located at or after any such
new bad blocks, however, will turn to
garbage due to the implicit renumbering
of all OS/8 blocks past those points.
Table 10 lists normal formatter messages, operator error messages, and
program error messages.
Table 10
RLFRMT Formatter Messages
1.

Normal Messages
Message

Meaning

RLFRMT Vvp

Identifies start of operations.
"v" is version number, "pH is
patch level letter.

DRIVE

Requests user to
type
number and RETURN key.

UNFORMATTED (NEW) DISK PACK

drive

Disk does not contain OS/8 bad
block lists, either because the
disk .is brand new or because
these lists have been destroyed
by
non-DIGITAL
software
or
diagnostic programs.
(continued on next page)

Table 10
(Cont.)
RLFRMT Formatter Messages
1.

Normal Messages (Cont.)
Meaning

Message
OS/8 (OLD) DISK PACK

Disk contains valid OS/8
bad
block lists.
(A formatted pack
contains octal 0123 in words 100
- 177 of sector 16 (octal) of
surface a of cylinder 0).

SERIAL NUMBER xxxxxxxxxx

The serial number is the ten
digit octal number assigned to
the pack at time of manufacture.

FACTORY-DETECTED BAD BLOCKS

The list of bad blocks found at
manufacturing time is printed in
the format "d nnnn", where d=A,B,
or C (the device) and nnnn = the
block number on that device which
is bad.

PREVIOUS OS/8 BAD BLOCKS

The current OS/8 bad block
are printed.

NEWLY-FOUND BAD BLOCKS

The list of bad blocks just found
by read-checking the entire disk
is printed.

NEW OS/8 BAD BLOCKS

This list results from combining
the previously printed lists.
It
is the list that is written on
the pack as the new OS/8 bad
block lists.

FORMAT PACK WITH THIS NEW LIST?

User types "Y" or "N" to allow or
prevent writing the new OS/8 bad
block lists.

DONE

Indicates that new OS/8 bad block
lists have been written on the
pack.
The pack now
may
be
removed if desired.
"DONE" is
always followed by "DRIVE?" to
allow formatting another pack.

lists

Operator Error Messages
Message

Meaning

PLEASE SPECIFY DRIVE NUMBER
(0-3) ON WHICH PACK TO BE
FORMATTED IS MOUNTED.

RLFRMT could not interpret user
response to "DRIVE?". User can
try again.

PLEASE WRITE-ENABLE DRIVE,
THEN HIT RETURN!

RLFRMT found the selected drive
write-locked
just
before
attempting to write new OS/8 bad
block lists on the pack.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _,__________ _ _

L -_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~

(continued on next page)

Table 10
(Cont.)
RLFRMT Formatter Messages
3.

Warning Messages (formatting can still be done)
Message

Meaning

WARNING: AN ADDITIONAL BAD
BLOCK FOUND.
ZERO DISK
BEFORE USE!

If the user permits the new OS/8
bad block lists to be written,
the OS/8 block numbering scheme
will be changed due to a new bad
block found during the read-check
of the entire pack. This will
make "garbage" out of any files
located at and after the bad
block number.

WARNING:
BAD BLOCK IN SYSTEM
AREA. DO NOT USE AS SYSTEM
DISK!

A new bad block was found during
the read-check of the pack. This
new bad block was on Device A
between
0
and 66
inclusive.
Since no bad blocks are allowed
in
this area for the system
device
(due
to
bootstrapping
constraints), permitting the pack
to be formatted disallows future
use
as
a
system
device.
Non-system use is unaffected.

WARNING: ALL FACTORY-WRITTEN
LISTS DESTROYED

All copies of the manufacturingdetected bad block list and disk
pack
serial number have been
destroyed
by
non-Digital
software.
Formatting continues,
assuming no factory-detected bad
blocks.

Error Messages

(f~rmatting

cannot be done)
Meaning

Message
FATAL I/O ERROR

If
this
message
appears
immediately,
it indicates that
the OS/8 bad block lists contain
physical I/O errors.
The pack
should not be used further
under
OS/8.
If this message appears
after attempting to write new
OS/8
bad
block
lists,
it
indicates that an
I/O
error
occurred.
The most common cause
will be a write-locked drive.
(continued on next page)

Table 10
(Cont.)
RLFRMT Formatter Messages

Error Message (formatting cannot be done)
Message

(Cont.)
Meaning

CANNOT FORMAT DISK

All error messages end with this
one,
to
indicate
that
the
formatting operation has failed.
This message is always followed
by "DRIVE?" to allow formatting
another pack.

OVER 15 BAD BLOCKS ON
ONE DEVICE

The new OS/8 bad block lists to
be written contain more than the
maximum
number of bad blocks
supported under OS/8.

OVER 63 NEWLY-FOUND
BAD BLOCKS

Indicates RLOI hardware problem
detected during read-check
of
disk or a pack with more than 63
bad blocks.
RLOI
diagnostics
should
be run and the drive
and/or controller fixed before
attempting to format disk packs.

5.5

System Building

The following procedure is used for building a system.
1.

Format the disk pack as described in Section 5.4.1.

Run BUILD from any device. BUILD is the system generation
program for OS/8
(see the OS/8 Handbook for a detailed
description of BUILD) .

Load RLSY.BN, RLO.BN, RLI.BN, RL2.BN, RL3.BN, or RLC.BN as
desired
(see Table 9 for names of devices in each group) .
For example, a complete system for two disk drives would
include SYS, RLOB, RLOC, RLlA, RLlB, and RLIC.
A partial
system to support all four drives could include SYS, RLOA,
RLOB, RLlA, RLIB, RL2A, RL2B, RL3A, and RL3B.

Issue the BOOT(strap)
command.
This will build an RLOI
system on RLOA, and start it.
It then asks a question as to
whether a new (zero) directory should be written on the new
device.
Answer yes to place a zero directory on the device.
RUN all programs with the RUN command until moved to the RLOI
disk pack.

APPENDIX A

RX02 BOOTSTRAP PROGRAM

PAL8-VlOA NO DATE
7301
7326
7327
7330
7350
7346

6751
6752
6753
6754
6755

AC1=CLL CLA lAC
AC2=CLL CtA CML RTL
AC6=CLL CLA CML lAC RTL
IRX02'S MUST RUN ON AN OMNI-BUS !I
AC4000=CLL CLA CML RAR
AC3777=CLL CLA CMA RAR
AC7775=CLL CLA CMA RTL
I
I DEVICE lOT SYMBOLIC EQUATES
I
LCD=6751
ILOAD COMMAND
XDR=6752
ITRANSFER DATA
STR=6753
ISKIP IF READY TO TRANSFER
SER=6754
ISKIP ON ERROR
SDN~6755
ISKIP ON DONE

I
0020
00020
00021
00022
00023
00024
00025
00026
00027
00030
00031

OOon

1061
1046
0060
3061
7327
1061
6751
7301
4053
4053
7004

00033
00034

6755
5054

00035
00036
00037
00U4U
00041
00042
00043
00044
00045
00046

6754
7450
5020
1061
6751
1061
0046
1032
3060
0360

00047
00050
00051
00052

4053
3002
2050
5047

I
I

*20

I
READ,

TAD
UNIT
ITRY NEXT COMBINATION OF DENSITY AND UNIT
TAD
CON360 IADDING IN 360
AND
CON420 IKEEPING ONLY 420 BITS
DCA
UNIT
ICYCLES 400,420,0,20,400""""
AC6
ICOMMAND TO READ DISK
TAD
UNIT
IUNIT AND DENSITY
LCD
ICOMMA~D TO CONTROLLER
AC1
ITO SET SECTOR AND TRACK TO 1
JMS
ISECTOR
TO CONTROLLER, LEAVES AC ALONE
LOAD
JMS
LOAD
lAND TRACK
ILEAVING A 2 IN AC~ SERVES AS LITERAL
LITRAL, 7004
I
I FOLLOWING IS PART OF WAIT LOOP, SAME SECONDARY BOOTS, OLD PRIMARY BOOT
I
START, SDN
IHAS DONE COME UP~ CODE STARTS HEREI
LOAD+l INO, GO CHECK FOR READY TO TRANSFER
JMP
I
I NOW, DONE OR ERROR
I
SER
ISKIP ON ~N ERROR, TRY ANOTHER DENSITY ETC.
INASTY, AC-2 FOR ABOUT TO DO SILO, 0 ON START-UP
SNA
ISTART-UP, GO SET UP UNIT, THEN READ TO SILO
JMP
READ
lAC ALREADY 2, PUT IN UNIT, DENSITY
TAD
UNIT
LCD
ITO EMPTY THE SILO
TAD
UNIT
ISET UP LOC 60 FOR OLD SECONDARY BOOT
AND
CON360 IKEEPING ONLY DENSITY BIT
TAD
LITRAL IADDING IN 7004, BECAUSE THAT'S WHAT SYS WANTS
DCA
RX1SAV IOLD SECONDARY BOOT MOVES IT TO HANPLER
CON360, 360
ILITERAL; EXECUTES IN LINE AS A NO-OP
/FALLS THRU TO NEXT PAGE OF LISTING
I
I
I
I FOLLOWING CODE SAME AS OLD PRIMARY BOOT
I
JMS
LOAD
IGRAB NEXT ITEM FRO" SILO
ITRADITION; SECONDARY BOOT STARTS LOADING AT 2 I
DCA
2
ISZ
50
IINCREMENT LOAD ADDRESS
JMP
47
IGO BACK FOR ANOTHER
I
I SECONDARY BOOT LOADS OVER PRIMARY BOOT UNIT LOCATION 47 IS LOADED,
I THEN CONTROL PASSES TO SECONDARY BOOT
I

A-l

RX02 BOOTSTRAP PROGRAM
00053
00054
00055
00056
00057

0000
6753
5033
6752
5453

LOAD,

I
I
I
I
I
00060
00061

0420
0020

o
STR
JMP
XDR
JMP

START
LOAD

ISUBROUTINE TO GIVE AND TAKE DATA FROM CONTROLLER
lIS HE READY TO TALK TO US?
INO, IS HE PERHAPS DONE WITH SILO, OR IN ERROR?
IYES, DATA IN OR OUT;IF DATA TO CONTROLLER, AC UNCHANGED
INO MAGIC, JUST EXIT FROM SUBROUTINE

60 GOES TO OLD SECONDARY BOOT
61 HAS DENSITY AND UNIT THAT BOOTED SUCCESSFULLY

CON420,
RXISAV, 420
UNIT,
20

IUSE IT TO HOLD 420 LITERAL TO START OUT
IUNIT 20+7004 TO GO TO SYS HANDLER
I<DENSITy 400>+<UNIT 20> THAT BOOTED OK
ft

A-2

APPENDIX B

RLOI BOOTSTRAP PROGRAM

AC0001=CLA lAC
AC0003=CLA CLL CML lAC RAL
AC0006=CLA CLL CML lAC RTL
AC2000=CLA CLL CML RTR
00001
00002
00003
00004

6600
7201
4027
1004

BOOT,

00005

4027

JMS IO

00006
00007
00010
00011
00012
00013
00014

6615
7002
7012
6615
0025
7004
6603

RRSI
BSW
RTR
RRSI
AND C377
RAL
RLCA

00015
00016
00017
00020
00021
00022
00023
00024

7325
4027
7332
6605
1026
6607
7327
4027

00025
00026

0377
7600

00027
00030
00031

0000
6604
6601

00032
00033
00034
00035

5031
6617
5427
5001

/CLEAR CONTROLLER REGISTERS
/CLEAR DRIVE REGISTERS

RLDC
ACOOOI
JMS IO
TAD

/AC=1004 (BYTE MODE READ HEADER
/FUNCTION). NOTE THAT THIS WORD
/MUST BE AT LOC 00041
/READ NEXT HEADER IN ORDER TO
/FIND OUT CURRENT CYLINDER
/READ HEADER BYTE #1
/GET LSB OF CYLINDER
/READ HEADER BYTE #2
/CONSTRUCT CYLINDER ADDRESS
fUSE IT AS DIFFERENCE WORD TO
/SEEK TO CYLINDER 0, SURFACE 0
/AC=SEEK FUNCTION
/SEEK TO TRACK 0
/AC=SECTOR 20 (OS8 BLOCK 0)
/LOAD SECTOR ADDRESS

AC0003
Jl-1S IO

AC2000
RLSA
TAD C7600
RLWC
/LOAD WORD COUNT FOR 1 PAGE
AC0006
/READ FUNCTION
JMS IO
/READ SECONDARY BOOTSTRAP
/READING IN SECONDARY BOOTSTRAP PREVENTS "IO" FROM
/RETURNING. CONTROL CONTINUES IN SECONDARY BOOTSTRAP.
C377,
C7600,

377
7600

/SUBROUTINE TO DO I/O TO DISK
IO,
0
/EXECUTE THE FUNCTION
RLCB
RLSD
/WAIT UNTIL DONE
/NOTE: THIS WORD AND NEXT
/ONE MUST BE LOCATED HERE
/IN ORDER TO MATCH UP WITH
/SIMILAR INSTRUCTIONS CON/TAINED IN THE SECONDARY
/BOOTSTRAP.
JMP .-1
RLSE
JMP I IO
/NO ERROR; RETURN
/ERROR: TRY AGAIN
JMP BOOT

B-1

INDEX

ABSLDR, 15

Bad-block mapping,
on RLOl, 22
BASIC,
patch for BRTS, 4
BATCH,
use with RLOl, 23
BOOT program,S, 32
Bootstraps,
for RLOl, 6
for RX02, 5
BUILD program,S, 37

CDF instruction,
use with extended memory, 13
CIF instruction,
use with extended memory, 13
Command registers,
RLOl, 26, 27
Core Control Block,
altering with SAVECB, 17
use with FUTIL, 5

Data space,
RLOl, 28
Device names,
RLOl, 23
RX02, 18
Disk format,
RLOl, 25, 33
Distribution media, 3

Extended mode register, 14

FIELD pseudo-operator,
use with extended memory, 13
FORTRAN,
patch for FRTS, 4
FUTIL, 5

Hardware disk address,
RLOl", 28

Instruction set,
RLOl, 27
lOT instructions,
use with KT8A, 4

KT8A, 7-18

Loading instructions,
RLOl, 31
LXM instruction, 14

Memory address register,
RLOl, 25
MEMORY command, 12
Monitor head,
moving with PIP, 4

ODT, use with extended memory,
9-11

PAL8,
use with extended memory,
12-15
Patches,
for BRTS, 4
for FRTS, 4
PIP, 4

RESORC, 3
Restrictions on extended memory,
for ABSLDR, 15
for MEMORY, 12
for Monitor, 8
for START, 9
RL8A controller format, 25-27
RLFRMT, 33
messages, 34-37
RLOI disk, 22-37
bad-block mapping, 22
bootstrapping, 6, 32
building a system on, 37
command registers, 26-27
data space, 28

Index-l

INDEX (Cont.)

RLOl disk (Cont.),
devices A, B, and C, 23
disk format, 25, 33
handlers, 30
hardware disk addresses, 28
instruction set, 27
loading instructions, 31
memory address register, 25
RL8A controller, 25-27
RLFRMT, 33
ROM bootstrap, 32
sector address register, 26
word-count register, 26
ROM bootstrap,
for RL01, 32
RXOl diskette,
compatibility with RX02, 19
formatting with RXCOPY, 22
interleave scheme, 20

RX02 diskette,
device names, 18
formatting with RXCOPY, 19, 22
interleave scheme for dl.1aldensity, 21
SAVE command,
use with extended memory, 8-9
SAVECB program, 17
Sector address register, 26
START command,
restrictions on use, 9
VXAO device, 16
Word-count register, 26

Index-2

OS/8
Device Extensions
User's Guide
AA-D319A-TA
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______________ State ______________ Zip Code ______________
or
Country

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No Posta~le
Neeessarv
if Mai led in the
United States

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BUSINESS REPLY MAIL
FIRST CLASS PERMIT NO.33 MAYNARD MASS.
POSTAGE WILL BE PAID BY ADDRESSEE

RT/C SOFTWARE PUBLICATIONS ML 5-5/E45
DIGITAL EQUIPMENT CORPORATION
146 MAIN STREET

MAYNARD, MASSACHUSETTS

01754

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