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EK-RKV11-OP-001

March 1977

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Document:	RKV11-D Disk Drive Controller Users Manual Jul1977
Order Number:	EK-RKV11-OP
Revision:	001
Pages:	34
Original Filename:	http://bitsavers.org/pdf/dec/qbus/EK-RKV11-OP-001_RKV11-D_Disk_Drive_Controller_Users_Manual_Jul1977.pdf

OCR Text

RKV11-0
disk drive controller
user's manual

EK-RKV11-0P-001

digital equipment corporation. maynard, massachusetts

Preliminary Edition, March 1977
1st Edition, July 1977

The material in this manual is for informational
purposes and is subject to change without notice.
Digital Equipment Corporation assumes no responsibility for any errors which may appear in this
manual.
Printed in u.s.A.

This document was set on DIGITAL's DECset-SOOO
computerized typesetting system.

The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
DEC
DECCOMM
DECsystem-l0
DECSYSTEM-20

DECtape
DECUS
DIGITAL
MASSBUS

PDP
RSTS
TYPESET-8
TYPESET-II
UNIBUS

CONTENTS

Page
CHAPTER 1

GENERAL DESCRIPTION

1.1
1.2
1.2.1
1.2.2
1.2.2.1
1.2.2.2
1.2.2.3
1.2.2.4
1.2.2.5
1.2.2.6
1.2.2.7
1.2.2.8
1.2.2.9
1.3
1.4
1.5

INTRODUCTION . . . . . . . . . . . . .
FUNCTIONAL DESCRIPTION . . . . . .
Disk Drives . . . . .
RKVI1-D Controller
Control Reset .
Seek Function
Drive Reset Function ..
Write Lock Function .
Write Function . . . . . . .
Read Function . . . . . .
Write Check Function
Read Check Function .
Hardware Poll . . .
PHYSICAL DESCRIPTION ..
SPECIFICATIONS
RELATED DOCUMENTS

CHAPI'ER2

INSTALLATION

2.1
2.2
2.3
2.4
2.5
2.6
2.6.1
2.6.1.1

INTRODUCTION . . . . . . . .
POWER REQUIREMENTS .. .
CABLING REQUIREMENTS ..
RKV11-D OPTION CONFIGURATIONS
INSTALLATION PROCEDURE
INSTALLATION TESTING
.....
Procedure
Toggle Routines

CHAPTER 3

PROGRAMMING CONSIDERATIONS

3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.2.6
3.2.7
3.3
3.4
3.5
3.6

INTRODUCTION . . . . . . . . . . . .
DEVICE REGISTERS AND ADDRESSES
Drive Status Register (RKDS)
Error Register (RKER) . . . . . . . .
Control Status Register (RKCS) .. .
Word Count Register (RKWC) . . . .
Current Bus Address Register (RKBA)
Disk Address Register (RKDA)
Data Buffer Register (RKDB)
DATA FORMAT . . . . . . . .
PROGRAM INTERRUPTS
TIMING CONSIDERATIONS ..
POWER FAIL . . . . . . . . . .

iii

1-1
1-2
1-2
1-3
1-3
1-4

1-4
1-4
1-4

1-5
1-5
1-5
1-5
1-5
1-6
1-7

2-1
2-1

2-2
.

2-2

2-2
2-4
2-4
2-4

3-1
3-1
3-1
3-3
3-5
3-7
3-8
3-8
3-9
3-9
. 3-10
.. 3-11
. .. 3-11

FIGURES

Title

Figure No.
1-1
1-2
2-1

...... .
RKVI1-D Disk Drive System
RKVII-D Controller, Functional Block Diagram
Mounting Information . . . . . . . . . . . . . .

Page
1-1
1-2
2-3

TABLES

Title

Table No.
1-1
1-2
2-1
2-2

Page
1-3

RKVI1-D Registers
Specifications
Power Specifications
Diagnostic Programs

1-6

2-1
2-4

PREFACE

This manual provides the user with information on the RKVII-D Disk Driver Controller. Discussions
in the manual deal with general descriptions of the RKVII-D controller. Detailed descriptions are
found in the RKVII-D Disk Driver Controller Maintenance Manual-available on microfiche. For
detailed coverage of the RKOS disk drive, refer to the RKOS Disk Drive Maintenance Manual
(EK-RKSJF-MM-OOl).
Although control signals and data are transferred between the RKVII-D controller and the LSI-II
bus, it is beyond the scope of this manual to cover the operation of the bus itself. Detailed information
regarding the LSI-ll bus may be found in the Microcomputer Handbook (EB-07948-S3).
Occasional reference is made to engineering drawings not contained in this manual. These drawings
are in the RKVII-D Moving Head Disk Driver Controller Engineering Drawings Manual; a copy is
supplied with each RKVII-D controller. That manual contains current RKVII-D prints, updated to
the time the equipment is shipped.

)

-----------

-----~~------

CHAPTER 1
GENERAL DESCRIPTION

1.1 INTRODUCTION
The RKVII-D is a controller for RK05 mass memories capable of communicating with up to eight
daisy-chained disk drives (Figure 1-1). The system is block-oriented but is capable of transferring from
I to 216 consecutive data words without reinitiation or processor intervention. These data transfers
occur on the LSI-II bus at the Direct Memory Access (DMA) level of communication.

For simplicity and clarity, the illustrations and descriptions contained in this manual are representative of a system utilizing only RK05J disk drives. RK05F drives, however, may also be used on the
RKVII-D controller. The RK05F is a nonremovable media disk drive. It is essentially identical to the
RK05J except that it has twice the storage capacity (achieved by doubling the track density).
The RK05F was designed to appear to the RKVII-D as if two "logical" RK05J drives were connected
to it. This design feature permits RK05J and RK05F drives to co-exist on the controller in any PDP-II
computer system. The RK05F utilizes two consecutive drive positions on the Drive bus instead of the
single position utilized by an RK05J. The first of the two "logical" consecutive drive positions must
always be an even number (Le., 0-1, 2-3, 4-5, or 6-7).

M7269
BUS
INTERFACE

f
....

RKVll-0 ADAPTER BUS
(60 ft. maximum)

---!~...

DR BUS
(60ft. maximum)

RKVll-D
CONTROLLER

M930
TERMINATOR
11-5154

Figure 1-1

RKVII-D Disk Drive System

I-I

1.2 FUNCTIONAL DESCRIPTION
The RKVII-D controller and the RK05 disk drive form the disk drive system, which interfaces with a
PDP-l1/03 processor via the LSI-II bus. The RKVII-D is implemented on five functional modules
(M7254, M7255, M7256, M7268, and M7269) and interfaces with the RK05 disk drive via a drive bus
(DR BUS) as shown in Figure 1-2.

til

III

BUS DAL LINES

I
I
II

M7255
DISK
CONTROL

RKV11·D MOUNTING BOX

;:)
~

r;;----- - -

BUS CONTROL LINES

M7269
BUS
CONTROL

BUS 0 LINES
CONTROL LINES

M7266
DATA
PATHS

I
M7268
RK11
BUS ADAPTER

I
r

M7264
STATUS
CONTROL

DRBUS

r ;;;8;-1

- - - - - .L

SUPPLY

"I;

RK06
DISK
DRIVES

I
I

I POWER

L_ ~

11·6152

Figure 1-2 RKVII-D Controller, Functional Block Diagram

1.2.1 Disk Drives
The RK05 is a moving head disk drive that uses RK03-KA disk cartridges for data storage. Data is
stored on both sides of the disk by a pair of movable heads, which are always positioned over opposing
surfaces of the same cylinder. Each side of the disk contains 203 10 tracks, each of which contains 1210
sectors capable of storing 4008 or 256 10 data words.
The sector format consists of 15 8 words of preamble terminating in a sync bit followed by a one-word
header, 4008 data words, a one-word checksum, and one word of postamble. A sector pulse indicates
the beginning of each sector. The index pulse occurs during the last sector, and the sector following the
index pulse is sector O.
The DR BUS has up to eight disk drives connected in daisy-chain fashion, each of which can be write
protected either by an RKVII-D controller Write Lock function or by manual intervention.
On a disk cartridge, the upper surface is defined as surface 0 and is active when RKDA 04 (SUR) is
clear. If a data transfer requires an overflow from surface 0, SUR is set automatically, and surface 1
(the lower surface of the cartridge) is activated at sector O. If a data transfer requires an overflow from
surface 1, the RKVll-D automatically moves the disk drive heads to the next cylinder, checks the
header word to verify head positioning, and resumes the data transfer at sector 0 of surface O. Attempting this cross-cylinder operation from surface 1 of the last cylinder will result in an error condition
(RKER 14-0VR).
1-2

For more detailed information on the disk drive operation and the related power supply, refer to the
RK05 Disk Drive Maintenance Manual (EK-RK5JF-MM-00l)-available on microfiche. That manual also contains a complete description of the DR BUS lines.
1.2.2 RKVll-D Controller
The RKVII-D is divided into five major functional units, as shown in Figure 1-2. The Status Control
module initiates the programmable RKVI1-D functions and monitors logic status conditions. The
Disk Control module monitors disk drive status conditions and controls all disk drive functions. The
Data Paths module transfers parallel data to and from the LSI-II bus and serial data to and from the
disk drives. The RKll Bus Adapter module serves as a connection point for th.e DR BUS, passing the
bus from the M7255 module to the RK05. The M7268 also adapts the three RKI1-D modules to
communicate with the RKVII-D Bus Control module (M7269). The Bus Control module interfaces
the RKVII-D with the LSI-II bus for address selection and controls DMA data transfers and interrupt sequences. The Bus Control module is located in the PDP-ll/03 processor and connects to the
Adapter module via the Adapter bus.
The RKV11-D contains seven 16-bit programmable hardware registers, addressed from the LSI-11,
that provide the software interface for the RKVII-D and the LSI-II bus. Table 1-1 lists these registers
and their addresses.
Table 1-1

RKVll-D Registers

Name

Abbreviation

Address

Drive Status Register
Error Register
Control Status Register
Word Count Register
Bus Address Register
(Current Memory Address)
Disk Address Register
Data Buffer Register

RKDS
RKER
RKCS
RKWC

177400
177402
177404
177406

RKBA
RKDA
RKDB

177410
177412
177416

Through software control, the RKVll-D can perform four control functions (Control Reset, Seek,
Drive Reset, and Write Lock) and four data transfer functions (Write, Read, Write Check, and Read
Check). The Hardware Poll feature (see section 4.3.4 ofRKVI1-D Maintenance Manual, EK-RKVl1MM-001) enables more than one disk drive to perform multiple Seek or Drive Reset functions simultaneously. The RKVII-D also initiates an interrupt sequence on the LSI-II bus in response to any of six
interrupt conditions described in Paragraph 3.4.
The data transfer functions (Read, Write, Read Check, and Write Check) all begin with an automatic
"implied" Seek operation. This allows the user of a single disk drive system to ignore the Seek function
completely and initiate data transfer functions directly. The hardware poll logic is initiated only for
Seek and Drive Reset functions and not for the "implied" Seek portion of data transfer functions.
1.2.2.1 Control Reset - The Control Reset function initializes all internal registers and flip-flops and
clears all of the bits of the seven programmable registers except RKCS 07 (READY), which it sets, and
RKDS 00 through 11, which are not affected. Disk drive operation is only affected indirectly, as a
result of RKVI1-D logic being cleared.

1-3

Control Reset serves as an effective "abort," because it terminates all controller action; however, care
should be taken during a Write operation as the abort does not occur until completion of the current
sector. If a Control Reset function is used to abort a function in process to allow a high-priority user
access to a disk drive, that drive must first be checked for head motion (indicated by RKDS 06Read/Write/Seek Ready). If the function is initiated before the heads have stopped, a hard error
results; after which a Drive Reset function must be performed on that drive before it can be used again.
1.2.2.2 Seek Function - For a Seek function, the RKVII-D directs the selected disk drive to move its
head mechanism to the cylinder address specified by RKDA 05-12. When this portion of a Seek has
been initiated, the controller returns to the Ready state (RKCS 07). If the specified cylinder address is
greater than 3128 , the function is aborted and bit 06 (Nonexistent Cylinder) of the RKER is set. RKCS
06 (IDE) then determines the program reaction.
The selected disk drive completes the Seek function by moving its head mechanism to the desired
cylinder, whereupon RKDS 06 (R/W /S RDY) is set. The time required to initiate a Seek function is
normally 1 ILS but may range up to 3.3 ms if an attempt is made to abort a Write function. Head
movement may take up to a maximum of 80 ms.
1.2.2.3 Drive Reset Function - For a Drive Reset function, the controller directs the selected disk
drive to move its head mechanism to cylinder address 000 and reset all active error status lines. To the
controller, the Drive Reset function is the same as a Seek function, even to the manner in which the
hardware poll logic is used; however, a Drive Reset function can take much longer than a Seek function to execute. The time required to complete a Drive Reset function depends on the physical position
of the head mechanism at the time the function is initiated and therefore may take a maximum of two
seconds.
1.2.2.4 Write Lock Function - The Write Lock function write-protects a selected disk drive until the
condition is overridden by operation of the corresponding WT PROT (write protect) switch on the
disk drive (refer to RK05 Disk Drive Maintenance Manual, EK-RK5JF-MM-00l). The disk drive is
automatically write-enabled when power is first applied or when the disk drive RUN/LOAD switch is
set to RUN.
1.2.2.5 Write Function - For a Write function, the controller automatically performs an "implied"
Seek operation. When that is completed, the next header word is read and checked for correct cylinder
identification (cylinder address). If the header is correct, the controller begins the Write operation
when the Sector Counter (RKDA 00-03) equals the Sector Address (RKDS 00-03), hereafter referred
to as SC = SA (RKDS 04).
A preamble consisting of 15 words of zeros is written, followed by a sync bit. Then the header word is
rewritten automatically, followed immediately by the data words for the sector. As the data words pass
through the controller, a one-word checksum word is calculated and automatically written after the
last sector data word, followed by one word of zeros for the postamble. If the cylinder address is
incorrect, the controller makes 16 attempts to establish the correct cylinder address before the function
is aborted, setting RKER 12 (Seek Error). (Compatibility with the RKII-C, which makes only one
attempt, may be achieved by cutting a jumper on the Status Control module.)
An RKWC overflow at any time from the start of the Write function stops the DMA data transfers
and sets RKCS 07 (RDY) at the end of the current sector. If the RKWC has not overflowed at the end
of a given sector, the function is continued at the next contiguous sector; however, if the last sector of
the disk cartridge is transferred without RKWC having overflowed, then RKER 14 (OVR) is set.

1-4

1.2.2.6 Read Function - For a Read function, the controller automatically performs an "implied"
Seek operation. When that is completed, the controller waits for SC = SA then reads and checks the
header word. If the cylinder address is correct, the controller continues reading the sector, and DMA
transfers the data words onto the LSI-II bus. If the cylinder address is initially incorrect, the controller
makes 16 attempts Uumper selectable to one, as previously noted) to establish the correct cylinder
address before the function is aborted, setting RKER 12. As the data words of a sector pass through
the controller, a one-word checksum word is calculated and compared with the checksum read from
the disk drive. If there is a discrepancy between the two checksums, RKER 01 (Checksum Error) is set,
and the controller reaction is determined by RKCS 06 (IDE) and RKCS 08 (SSE). An RKWC overflow at any time from the start of the Read function stops the DMA data transfers and sets RKCS 07
(RDY) at the end of the current sector. If the RKWC has not overflowed at the end of the given sector,
the function is continued at the next sector.
1.2.2.7 Write Check Function - The Write Check function is used to compare the contents of memory
to the contents of a continuous block of data on a disk cartridge. The controller automatically performs an "implied" Seek operation, just as for a Write function and then reads and checks the next
header word. If the cylinder address is correct, the controller waits for SC = SA then begins reading
the rest of the sector (data and checksum) while performing D MA transfers for each data word. Each
data word from the disk drive is compared, bit by bit, with memory data from the LSI-II bus. The disk
drive checksum, in turn, is compared with the checksum calculated by the controller. If any bit is
found to be in error, RKER 00 (Write Check Error) is set. Controller reaction is then determined by
RKCS 06 (IDE) and RKCS 08 (SSE). The Write Check function may be performed on a short sector
(less than 256 data words) as long as the number of words write-checked is equal to the number of
words previously written into the sector.
1.2.2.8 Read Check Function - The Read Check function is identical to a normal Read function,
except that no DMA data transfers occur. Only the checksum is calculated and compared with the
checksum read from the disk drive. This function enables the program to know beforehand if a given
block of data is readable and error free. Because the Read Check is essentially a parity check, it must
be performed on a whole-sector basis only.
1.2.2.9 Hardware Poll - The controller is capable of permitting any or all disk drives to perform a
Seek or Drive Reset function simultaneously. The hardware poll feature in the disk control module
identifies the logical disk drive in RKDS 13-15 (DRIVE IDENT) for any disk drive that has completed
a Seek or Drive Reset function. This poll causes an interrupt if RKCS 06 (IDE) is set, the controller is
in the Ready state (RKCS 07 set), and the controller is not already attempting to initiate an interrupt
from some other function. If two or more disk drives complete a Seek or Drive Reset function simultaneously, the controller interrupts once for each disk drive and identifies each in turn to the RKDS. In
this situation, the processor interrupt level must be raised in order to shut off interrupts, or else a
second interrupt will occur immediately after the first-causing the interrupt service routine to be
interrupted. Similarly, back-to-back interrupts will also result from directing the heads to a cylinder at
which they are already positioned-with the first interrupt coming from the initiation of a Seek function and the second coming from notification from the hardware poll that the heads are already at the
desired address.

1.3 PHYSICAL DESCRIPTION
The RKVll-D controller utilizes six modules: M7254, M7255, M7256, M7268, M7269, and M930.
The M930 is a bus terminator and is installed on the last RK05 disk drive in the system. The M7269
module is located in the PDP-l 1/03 processor box. The remaining four modules are in the RKVll-D
box, which is 381.00 mm deep, 88.90 mm high, and 482.60 mm long (15.00 in X 3.50 in X 19.00 in).
The RKVII-D box is hard-mounted in the cabinet and also contains an H780 power supply. Detailed
cabling and module utilization information can be found in unit assembly drawing D-UA-RKVllD-O.

1-5

An RKV 11 disk drive system consists of the controller, the RK05 disk drives, and the necessary
cabling. The LSI-II bus connects the RKVll-D Bus Control module and the PDP-lI/03 processor.
The Drive bus (DR BUS) connects the controller and the disk drives in a daisy-chain manner. To be
compatible with the RKVll-D, each RK05 disk drive requires an M7700, Revision J or later, and a
back panel, Revision A or later. The M7700 card of each disk drive contains a rotary switch that
defines the logical disk DR BUS position. The first disk drive on the DR BUS is normally switched to
position 1 and is designated disk drive 0 and so on through disk drive 7. This configuration may be
varied as DR BUS length allows. The maximum length of DR BUS is 1524 cm (50 ft). For more
information on the disk drive and disk drive system, refer to the RK05 Disk Drive Maintenance
Manual (EK-RK5JF-MM-00l).

1.4 SPECIFICATIONS
Table 1-2 specifies the RKVII-D parameters in the areas of environmental limits, logic format, timing
format, and power requirements and sets forth model designations.
Table 1-2 Specifications
Category

Parameters

Environmental Limits
DIGITAL Class A Environment:
Temperature
Relative Humidity

15°C to 32°C (60 0 P to 90°F)
20% to 80% (no condensation)

Engineering Specifications:
Temperature
Relative Humidity

5°C to 50°C (41°F to 122°F)
10% to 95% (no condensation)

Input Voltage:
RKVII-DA
RKVII-DB

100-127 V rms, 50 ± 1 Hz or 60 ± 1 Hz
200-254 V rms, 50 ± 1 Hz or 60 ± 1 Hz

Input Power:
RKVII-D
M7269

140 W maximum
+5 V @ 1.8 A maximum (9 W)

Format
Drive Format:

Data Word Format:

1 disk cartridge/disk drive
203 cylinders/disk drive
2 disk surfaces/disk drive
2 tracks/cylinder
12 sectors/track
16-bit data word
256 10 = 4008 data words/sector
3072'0 = 60008 data words/track
623,616'0 data words/surface
1,247,232'0 data words/disk drive
Bit density - approximately 2200 bpi

Recording Method:

Double frequency

Data Transfer Path:

LSI-II bus DMA
1-6

~--

----~--~--

-------_._--

1.5 RELATED DOCUMENTS
These documents pertain to the RKVII-D controller: RK05 Disk Drive Maintenance Manual (EKRK5JF~MM-OOl); Microcomputer Handbook (EB-07948-53).
~.

1-7

CHAPTER 2
INSTALLATION

2.1 INTRODUCTION
The RKVII-D controller system configuration depends on the number of disk drives used in a particular disk drive system. Each RKVII-D can control up to eight disk drives. Each cabinet contains the
power controls for the associated disk drives and all the necessary cabling. For details regarding disk
drive installation, refer to RK05 Disk Drive Maintenance Manual (EK-RK5JF-MM-00l).
2.2 POWER REQUIREMENTS
The RKVII-D controller has a +5 V power supply positioned in its mounting box. Table 2-1 lists
power specifications.
Table 2-1

Power Specifications

RKVII-D Box
Input voltage:
RKVII-DA
RKVII-DB

100-127 V rms, 50 ± 1 Hz or 60 ± 1 Hz
200-254 V rms, 50 ± 1 Hz or 60 ± 1 Hz

Input power

140 W maxim urn

Output power (to RKVII-D modules)

+5 V ± 3%

Output protection

Current is limited to 1.2 times maximum
normal rating
+5 V is limited to +6.3 V

Output ripple

Less than 150 m V p-p

Line protection

115 V input - 5 A fast blow fuse
230 V input - 2.5 A fast blow fuse

Console

DC ON indicator (under bezel)

Rear panel controls

AC ON/OFF power switch

Backplane signals received from power supply

BPOK H (BUS AC LO L)
BDCOK H (BUS DC LO L)

Cooling

Two self-contained fans provide
30 ft 3/min at 200 linear ft/min air flow

M7269 input power

+5 V @ 1.8 A maximum

2-1

2.3 CABLING REQUIREMENTS
There is no physical LSI-II bus between the RKVII-D box and the LSI-II central processor. Two
120 ohm, 40 conductor flat cables (BC05-L) called the Adapter bus connect the M7268 module in the
RKVII-D box to the M7629 module in the LSI-II box. Both modules contain the mechanical connection points and logic to control this bus.
The DRive BUS connects the RKVII-D to the RK05 disk drives in the system. The cable between the
first disk drive and the RK V II-D box consists of a pair of 120 ohm, 40 conductor flat cables (700902602). Cabling between each of the RK05s is supplied with each disk drive (BC II-A). The disk control
logic on the M7255 module connects through the RKVII-D back panel to the M7268 module which
makes the physical connection to the DR BUS (the M7268 itself contains no disk control logic).
2.4 RKVII-D OPTION CONFIGURATIONS
All jumpers are the same as on the RK II-D. For details refer to the Field Maintenance Print Set
(MPOO223). However, no bus interrupt priority jumper plug is required on the M7254.
2.5 INSTALLATION PROCEDURE
The RKVII-D subsystem can be mounted easily in any 48.260 cm (19 in) rack. The RKVII-D ships in
two containers: the small one is shipped inside the larger one. The larger container holds the RKVII-D
box and the mounting hardware kit necessary to put the RKVII-D into the cabinet. The kit contains
all necessary screws, nuts, and mounting brackets.
The small container holds two modules; two cables, and a module/cable assembly for connection to an
LSI-II system. For module and cable utilization descriptions, refer to the RKVII-D unit assembly
drawing (D-UA-RKVII-D-O).
A standard 48.260 cm (19 in) rack has a pattern of holes spaced 1.270 cm and 1.588 cm (1/2 in and 5/8
in). The pattern repeats itself every 4.4450 cm (1-3/4 in) (Figure 2-1).

2-2

- - - - - - - 1 . 1 " ' - .19" TYP
3/8" TYP

FRONT OF BOX( PANEL ReMOVED)

oil 114" TYP

-I

19"

11-3308
11-3308

~---17-518"

---401.1

10-0---13.50"

~=====::='\iT
c::::=:::J

POWER SUPPLY

AIR

3-1/2"

J
FRONT

1.l:::::=:====~~
--jr-f-- 'I12

--------I-I

19"------...,.1

RKV1'-D
MODULES

11-3303
11-3304

fRONT VIEW

1/4"

0
0

~l,~:,:,::~-~rr*FRONT PANEL

1-3/4"

.112"

5/8"

1___ - +
5/8"

0
0

3-112"

1/2"

L_~~_ ++
5/8"

5/8 11

0
0

1/2"

..i...

I-

18-5/16"

-I
11- 3297

Figure 2-1

Mounting Information

2-3

2.6 INSTALLATION TESTING
To ensure that the RKVll-D system is properly installed and operational, installation testing is performed by running the diagnostic programs listed in Table 2-2. If performance of these tests fails to
reveal errors, assume that the RKVl1-D is operational and that it has been correctly installed. These
diagnostics are supplied with the RKVll-D. Instructions and descriptions regarding their use are
supplied to each field office on microfiche. Hard copies are available through the Software Distribution Center, Digital Equipment Corporation, Maynard, MA 01754.
Table 2-2 Diagnostic Programs
Title

Number

RKll Performance Exercisor
RKll Utility Package
RKll Basic Logic Test I
RKII Basic Logic Test II
RK 11 jRK05 Dynamic Test

MD-I1-DZRKH-F-PB
MD-II-DZRKI-D-PB
MD-II-DZRKJ-D-PB
MD-II-DZRKK-D-PB
MD-II-DZRKL-D-PB

2.6.1 Procedure
Use a scratch pack to ensure that the RK05 can be safely powered-up and that the heads can be
successfully loaded. All RK05s should be properly installed and adjusted prior to testing
the RKVII-D. The "oscillating seek" program may be used to assist in performing a head alignment.
Refer to Toggle Routines, Paragraph 2.6.1.1.
Diagnostics may be loaded in.to the LSI-II from the RKDP pack if available. If not available or if the
RKVII-D requires repair, then the diagnostics may be loaded into the LSI-II via a PRSOI paper tape
reader.
If the system contains an REVII bootstrap module, the RKDP pack may be booted upon the application of power to the system. If the system does. not contain anREVl1 bootstrap or if the bootstrap is
defective, the "boot" routine may be used to boot the RKDP pack. See Toggle Routines, Paragraph
2.6.1.1.

To be acceptable, the RKVll-D must run error free (use a scratch pack):
Two passes
Two passes
One pass

RKll Basic Logic Test I
RKll Basic Logic Test II
RK 11 Performance Exercisor.

All customer system software should also be verified as a part of installation testing.
2.6.1.1 Toggle Routines - These routines aid installation and maintenance testing. They are loaded
into the LSI-II using the hardware ODT microcode, allowing the use of the operator console instead
of the traditional console switch panel normally associated with larger PDP-II central processors. The
hardware ODT microcode automatically begins execution when the LSI-II is halted, either under
program control or by momentary assertion of the HALT switch mounted on the LSI-II processor
box. A detailed description of hardware ODT commands is contained in the Microcomputer Handbook (EB-07948-53).

2-4

Oscillating Seek Program - This program aids in checking servo signals and performing head alignment. Load the program into memory using the hardware ODT feature and select the desired drive,
cylinder, and surface addresses. The program will then cause the drive to seek back and forth between
the cylinder addresses contained in the high and low bytes of RO. If both bytes of RO contain the same
cylinder address, the drive will stay at that cylinder.
Equivalent Track Addresses
Decimal

Octal

4
64

100
125
151
175
312

85
105
125
202

;RO = two cylinder addresses, one in each byte
;RI = 177404 (RKCS address)
;R2 = drive number in bits 15, 14, 13; surface number in bit 4; all others are zero.
001000
001002
001004
001006
001010
001012
001014
001016
001020
001022
001024
001026
001030
001032
001034
001036
001040
001042
001044
001046
001050
001052

000005
010003
042703
000377
000241
006003
006003
006003
010361
000006
050261
000006
012711
000011
105711
100376
032737
000100
177400
001774
000300
000753

START:
LOOP:

1$:

2$:

RESET
MOV
BIC

RO, R3
#377,R3

CLC
ROR
ROR
ROR
MOV

R3
R3
R3
R3,6(Rl)

BIS

R2,6(R1)

; load drive, surface address

MOV

#1l,(R1)

; load SEEK & GO

TSTB
BPL
BIT

(R1)
1$
#100,RKDS

; await ready
; await R/W IS RDY

BEQ
SWAB
BR

2$
RO
LOOP

)
2-5

; R3 =cylinder address
; mask for single address

; position address
; load cylinder address

; position second address

RK Boot Program - Use this program to boot an operating system from any RK05 when the system
does not contain a hardware bootstrap module or contains a defective bootstrap module.
;RO = drive number in bits 15, 14, 13; all others are zero.
;Rl = 177404 (= RKCS Address)
001000
001002
001004
001006
001010
001012
001014
001016
001020
001022
001024

000005
010061
000006
012761
177400
000002
012711
000005
105711
100376
005007

START:

1$:

RESET
MOV

RO,6(Rl)

MOV

#-256,2(Rl) ; load RKWC = -256

MOV

#5,(Rl)

; load READ & GO

TSTB
BPL
CLR

(Rl)
1$
PC

; test ready
; await ready
; force PC to absolute zero

; 10adRKDA

Format Program - This program allows the user to format an unformatted disk on any disk pack in the
system. Any information formerly contained on the disk is lost, and the entire disk is filled with the
contents of memory address 000000. When the program halts, check the contents of the RKER register (177402). It will contain 000100 if the format was successfully completed. If this register contains
any other data, the format did not complete successfully.
;RO = drive number in bits 15, 14, 13; all others are zero.
;Rl = 177404 (= RKCS)
001000
001002
001004
001006
001010
001012
001014
001016
001020
001022
001024
001026

000005
010061
000006
005161
000002
012711
006003
105711
100376
005711
100370
000000

START:
LOOP:

1$:

RESET
MOY

RO,6(Rl)

; RKDA = drive number

COM

2(Rl)

;RKWC =-1

MOV

#6003,(Rl) ; load write format, IBA + GO

TSTB
BPL
TST
BPL
HALT

(Rl)
1$
(Rl)
LOOP

2-6

; ready?
; await ready
; error?
; if not, LOOP

CHAPTER 3
PROGRAMMING CONSIDERATIONS

3.1 INTRODUCTION
This chapter discusses the software interface for the RKV11-D controller, including device registers
and their addresses, the interrupt process, timing considerations, and data format.
3.2 DEVICE REGISTERS AND ADDRESSES
All RKVII-D software control is accomplished by seven device registers. These registers are assigned
memory addresses and can be read or written into (except as noted), using instructions that refer to the
respective register addresses. The seven device registers, their bit assignments, and their memory
addresses are presented on the following pages. Unassigned and write-only bits are always read as
zeros. Any attempt to manipulate unassigned or read-only bits has no effect on the bit (except as
noted). The INIT signal refers to the initialization signal issued by the processor.
3.2.1

Drive Status Register (RKDS)
Address = 177400
NOTE
This register is a read-only register and contains the
selected drive status and current sector address.

D~IVE ID~NT
2

DPL

RK05

DRU

SIN

SOK

DRY

R!W!S
RDY

WPS

SC=
SA

SiCTOR 60UNTJR

0
CP-3137

)

Bit

Designation

Description and Operation

00-03

Sector Counter (SC)

These four bits are the current sector address of the
selected drive. Sector address 00 is defined as the
sector following the sector that contains the index
pulse.

Sector Counter Equals Sector
Address (SC = SA)

Indicates that the disk heads are positioned over
the disk address currently held in the Sector Address Register.

Write Protect Status (WPS)

Sets when the selected disk is in the write-protected
mode.
3-1

Bit

Designation

Description and Operation

Read/Write/Seek Ready
(R/W/S ROY)

Indicates that the selected drIve head mechanism is
not in motion and that the drive is ready to accept
a new function.

Drive Ready (DRY)

Indicates that the selected disk drive complies with
the following conditions:
a.

The drive is properly supplied with power.

The drive is loaded with a disk cartridge.

The disk drive door is closed.

The LOAD/RUN switch is set to RUN.

The disk is rotating at a proper speed:

The heads are loaded properly.

The disk is not in a DRU (bit 10 of RKDS)
condition.

Sector Counter OK (SOK)

Indicates that the Sector Counter operating in the
selected drive is not in the process of changing and
is ready for examination. If this bit is not set, the
Sector Counter is not ready for examination, and a
second attempt should be made.

Seek Incomplete (SIN)

Indicates that due to some unusual condition, a
Seek function cannot be completed. Can be accompanied by RKER 15 (Drive Error). Cleared by a
Drive Reset function.

Drive Unsafe (DRU)

Indicates that an unusual condition has occurred in
the disk drive, and it is unable to properly perform
any operations. Reset by setting the RUN/LOAD
switch to LOAD. If-when the switch is returned
to run-the condition recurs, an inoperative drive
can be assumed, and corrective maintenance procedures should begin. Can be accompanied by
RKER 15 (Drive Error).

RK05 Disk on Line (RK05)

Always set, to identify the selected disk drive as
RK05.

Drive Power Low (DPL)

Sets when an attempt is made to initiate a new
function or if a function is actively in process when
the control senses a loss of power to one of the disk
drives. Can be accompanied by RKER 15 (Drive
Error). Reset by a BUS INIT or a Control Reset
function.

3-2

Bit

Designation

Description and Operation

13-15

Identification of Drive (ID)

If an interrupt occurs as the result of a hardware
poll operation, these bits will contain the binary
representation of the logical drive number that
caused the interrupt.

3.2.2

Error Register (RKER)
Address = 177402
NOTE
This is a read-only register.
15

ORE

OVR

WLO

SKE

PGE

NXM

DLT

NXD

NXC

NXS

UNUSED
I

CSE

weE

I
CP-3138

Bit

Designation

Description and Operation

Write Check Error (WCE)

Indicates that an error was encountered during a
Write Check function as a result of a faulty bit
comparison between disk data and memory data.
Clears upon the initiation of a new function. This is
a soft error condition.

Checksum Error (CSE)

Sets while performing a Read Check or a Read
function as a result of a faulty recalculation of the
checksum. Cleared upon the initiation of any new
function. This is a soft error condition.

02-04

Unused

The remaining bits of the RKER are all hard errors and are cleared only by a BUS INIT or a control
reset function.

'\
)

Nonexistent Sector (NXS)

Indicates that an attempt was made to initiate a
transfer to a sector address greater than 13 8 •

Nonexistent Cylinder (NXC)

Indicates that an attempt was made to initiate a
transfer to a cylinder address greater than 312 8 •

Nonexistent Disk (NXD)

Indicates that an attempt was made to initiate a
function on a nonexistent drive.

Timing Error (TE)

Indicates that a loss of timing pulses for at least
5 f.LS has been detected.

Data Late (DLT)

Sets during a Write or Write Check function when
the multibuffer file is empty, and the operation is
not yet complete. Sets during a Read function
when the multibuffer file is filled, and the operation is not yet complete.

3-3

Bit

Designation

Description and Operation

Nonexistent Memory (NXM)

Sets if memory does not respond with a RPLY
within 20 J.LS of the time when the RKVll-D becomes bus master during a DMA sequence. Because of the speed of the RK05 disk drive, it is
possible that NXM will be accompanied by RKER
09 (Data Late).

Programming Error (PGE)

Indicates that RKCS 10 (Format) was set while initiating a function other than Read or Write.

Seek Error (SKE)

Sets if the disk head mechanism is not properly
positioned while executing a normal Read, Write,
Read Check, or Write Check function. The control
checks 16 times before flagging this error. A simple
jumper change will force the control to check just
once.

Write Lockout Violation (WLO)

Sets if an attempt is made to write on a disk that is
currently write-protected.

Overrun (OVR)

Indicates that, dudng a Read, Write, Read Check,
or Write Check function, operations on sector 13 8,
surface 1, of cylinder address 3128 were finished;
and the RKWC has not yet overflowed. This is essentially an attempt to overflow out of a disk drive.

Drive Error (D RE)

Sets if a function is either initiated or in process,
and
a.

One of the drives in the system senses a loss of
either ac or dc power; or

The selected drive is not ready or is in some
error condition.

3-4

---~~---

~-"~-----~---~---~~----

3.2.3

Control Status Register (RKCS)
Address = 177404

02
01
I
I
FUNCTION

I
ERR

SCP

IBA

FMT

SSE

ROY

IDE

UNUSED

00
GO

UNUSED

CP-3139

Bit

Designation

Description and Operation

GO (Write Only)

This bit can be loaded by the operator and causes
the control to carry out the function contained in
bits 01-03 of the RKCS (Function). Remains set
until the control actually begins to respond to GO,
which may take from 1 f.LS to 3.3 ms, depending on
the current operation of the selected disk drive (to
protect the format structure of the sector).

01-03

Function (Read/Write)

The Function register or function bits are loaded
with the binary representation of the function to be
performed by the control when a GO command is
initiated. These bits are loaded by the program and
cleared by BUS IN IT _A description of each of the
eight functions is given in Paragraph 1.2.2. The
binary codings are as follows:
Bit2

Bit 1

Bit 0

Operation

0
0
0
0
1
1
1

0
0
1
1
0
0
1
1

0
1
0
1
0
1
0
1

Control Reset
Write
Read
Write Check
Seek
Read Check
Drive Reset
Write Lock

04,05

Unused

NOTE: The RKll-D uses these bits as extended
address bits. Since the 11/03 BUS structure has no
provision for extended addressing, no connection is made to the bus from these bits on the
RKVII-D. They will respond as two unused
READ /WRITE bits in the status register; but like
the RKll-D, they will increment should the
RKBA overflow.

3-5

Bit

Designation

Description and Operation

Interrupt on Done Enable (IDE)
(Read/Write)

When set, causes the control to issue a bus request i
and interrupt to vector address 220 if:

Control Ready (ROY)
(Read Only)

Stop on Soft Error (SSE)
(Read/Write)

A function has completed activity.

A hard error is encountered.

A soft error is encountered and bit 08 of the
RKCS (SSE) is set.

d. RKCS 07 (ROY) is set, and GO is not set.
Indicates that the control is ready to perform a
function. Set by INIT, a hard error condition, or
by the termination of a function. Cleared by GO
being set.
If a soft error is encountered when this bit is set:

All control action will stop at the end of the
current sector if RKCS 06 (IDE) is reset, or

All control action will stop, and a bus request
will occur at the end of the current sector if
RKCS 06 (IDE) is set.

Unused

Format (FMT)
(Read/Write)

FMT is under program control and must be used
only in conjunction with normal Read and Write
functions. Used to format a new disk pack or to
reformat any sector erased due to control or drive
failure. Alters the normal Write operation, under
which the header is rewritten each time the associated sector is rewritten, in that the head positioner
is not checked for proper positioning before the
Write. Alters the normal Read operation in that
only one word, the header word, is transferred to
memory per sector. For example, a three-word
Read function in format mode will transfer header
words from three consecutive sectors to three consecutive memory locations for software checking.

Inhibit Incrementing the RKBA
(IBA)
(Read /W rite)

Inhibits the RKBA from incrementing during a
normal transfer function. This allows data transfers to occur to or from the same memory location
throughout the entire transfer operation.

3-6

Description and Operation

Bit

Designation

Unused

Search Complete (SCP)
(Read Only)

Indicates that the previous interrupt was the result
of some previous Seek or Drive Reset function.
Cleared at the initiation of any new function.

Hard Error (HE)
(Read Only)

Sets when any of RKER 05-15 are set. Stops a11
control action, and processor reaction is dictated
by RKCS 06 (lDE)-until cleared, along with
RKER 05-15, by INIT or a Control Reset function.

Error (ERR)
(Read Only)

Sets when any bit of the RKER sets. Processor reaction is dictated by RKCS 06 and RKCS 08 (IDE
and SSE). Cleared if a11 bits in the RKER are
cleared.

3.2.4 Word Count Register (RKWC)
Address = 177406

WC15:-

: : : : :wcoo

CP-3140

Bit

Designation

Description and Operation

00-15

WCOO-WClS (Read/Write)

The bits in this register contain the 2's complement
of the total number of words to be affected or
transferred by a given function. The register increments by one after each word transfer. When
the register overflows (all WC bits go to zero), the
transfer is complete and RKVI1-D operation is
terminated at the end of the present disk sector.
However, only the number of words specified in
the RKWC are transferred.

3-7

3.2.5 Current Bus Address Register (RKBA)
Address = 177410
15

CP-3135

Bit

Designation

Description and Operation

00-15

BAOO-BAI5 (Read/Write)

The bits in this register contain the bus address to
or from which data will be transferred. The register
is incremented by two at the end of each transfer.

3.2.6 Disk Address Register (RKDA)
Address = 177412
NOTE
This register will not respond to commands while the
controller is busy. Therefore, RKDA bits are loaded
from the bus data lines only in the Control Ready
(RDY - bit 07 of the RKCS) state and are cleared by
BUS INIT and Control Reset. The RKDA is incremented automatically at the end of each disk sector.
15

DR'IVE
2

SEL~CT
1

CY~INDER' ADDRE'SS
I

S~CTDR IADDRE~S

SUR
2

CP-3136

Bit

Designation

Description and Operation

00-03

Sector Address (SA)

Binary representation of the disk sector to be addressed for the next function. The largest valid address (or number) for the sector address is 13 8 •

Surface (SUR)

When active, enables the lower disk head so that
operation is performed on the lower surface; when
inactive, enables the upper disk head.

05-12

Cylinder Address (CYL ADDR)

Binary representation of the cylinder address currently being selected. The largest valid address or
number for the cylinder address is 3128 •

13-15

Drive Select (DR SEL)

Binary representation of the logical drive number
currently being selected.

3-8

-~------~--

--------~-

.--~----

3.2.7 Data Buffer Register (RKDB)
Address = 177416

DB15:_

:DBOO

CP-3134

Bit

Designation

Description and Operation

00-15

DBOO-DBI5 (Read Only)

The bits ofthis register work as a general data handler in that all information transferred between the
control and the disk drive must pass through this
register. Loaded from the bus only while the
RKVII-D is bus master during a DMA sequence.
NOTE
Address 177414 is unused.

3.3 DA TA FORMAT
Data is stored on the disk cartridge in groups of 12 sectors per track. Each of the 12 disk sectors
contains 256 10 words and is defined by physical sector marks. These sector marks generate a sector
pulse that is passed from the disk drive to the controller. Another similar physical disk mark, called an
index mark, defines the starting point for the sequence of sectors. The sector which follows a sector
containing the index mark is defined as sector O. All of the sectors are formatted identically in five
parts: preamble (terminated with a sync bit), header, data, checksum, and postamble.

PREAMBLE

SYNC BIT

HEADER

DATA

CHECKSUM

POSTAMBLE

15.WORDS
OF ZEROES

"1"

CYLINDER
ADDRESS

256,0 (400.)
WORDS

SECTOR
CHECKSUM

1 WORD
OF ZEROES

(1 WORD)

(1 WORD)
CP-3133

The preamble and postamble areas of a sector serve as boundaries before and after the information
major states (header, data, and checksum) to ensure compatibility between disk drives. (Refer to the
RK05 Disk Drive Maintenance Manual, EK-RK5JF-MM-001.)
The preamble consists of 15 8 words of zeros, adequate to guarantee that RD GATE will turn on during
a known zero data field under all conditions. The disk drive head then waits for the first" I " to occur
(sync bit) and begins to read with the header word. During a Write function, the syn.c bit is automatically written by hardware following the 15 8 words of zeros.

3-9

The header area of a sector consists of a single word containing the cylinder address from RKDA
05-12. Before a data transfer function is performed, the header word is read and checked against the
cylinder address portion of the RKDA to ensure that the disk drive heads are positioned at the proper
cylinder. The Write function always rewrites the header on the disk, using the cylinder address portion
of the RKDA. The sector format for a raw (unformatted) cartridge is written under program control in
conjunction with RKCS 10 (FMT) (refer to Paragraph 3.2.3).
The data area consists of 256 10 data words. These words, like all of the words in each area of the sector,
are 16 bits long.
The checksum area of a sector consists of a single word that is the checksum of all 256 data words. For
a Write function, the controller calculates a checksum and writes it on the disk cartridge following the
last data word. This checksum is compared by the controller to the checksum that it calculates whenever a Write Check, Read, or Read Check function is performed within a given sector.
Short portions (less than 256 data words) of a sector may be read or written as long as this short sector
is the last sector of the data transfer. When a short sector is written, the remainder of the sector is
automatically written with zeros. The Write Check function may be performed on a short sector as
long as the number of words write checked is equal to the number of words previously written into the
sector. Because the Read Check function is essentially a parity check, it must be performed on a wholesector basis only.

3.4 PROGRAM INTERRUPTS
A program interrupt is initiated by an interrupt request, which can only occur if RKCS 06 (IDE) is set.
Six hardware conditions can generate an interrupt request to the processor:
1.

The occurrence of a hard error condition RKCS 14 (HE).

The presence of a soft error condition RKCS 08 (SSE) is set and either RKER 00 (WCE) or
RKER 01 (CSE).

Completion of transfer of the designated number of words.

The acceptance (Address Acknowledge) of a Seek or Drive Reset function by the selected
disk drive, freeing the controller for hardware polling or a new function.

The initiation of a Write Lock function on a disk drive, indicating that the controller is free
to perform a new function.

The completion of hardware polling (RKCS 13 - SCP), indicating that the disk drive in the
DRIVE ID bits of the RKDS has completed a Seek or Drive Reset function (RKDS 06 RjWjS RDY).

The interrupt request level of the RKVI1-D controller is determined by the physical position of the
controller on the LSI-II bus. The DMA device closest to the LSI-II processor is usually the Memory
Refresh module REVl1 (DIGITAL Part No. M9400-YA), and, like all DMA devices, the RKVll-D
controller must be connected to the LSI-ll bus after the REVl1.

3-10

-----~

-~.~

~~~-.~

...

-.--~~.~.-

..... .

Because of the format structure of the RKVlI-D, any interruption of the Write function cannot be
tolerated until the end of the current sector, as it would result in what would be essentially an unformatted disk cartridge. As a result, outside intervention is inhibited until the current sector is completed, including Control Reset functions and processor initialize (BUS INIT) signals. This means that
such functions as Control Reset, Seek, and Write Lock, which take only a few microseconds to initiate,
can take as long as 3.3 ms if initiated during a Write function. For this reason, Seek, Drive Reset,and
Write Lock functions cause an interrupt as soon as the function is initiated, provided that RKCS 06
(IDE) is set.
3.5 TIMING CONSIDERATIONS
RKVll-D timing is a consideration in the performance of overlapping Seek or Drive Reset functions,
because these functions can be initiated on free disk drives while previous Seek or Drive Reset functions are in process on other disk drives. Thus, up to eight disk drives can be performing a Seek or
Drive Reset function simultaneously. The hardware poll logic of the disk control module generates an
interrupt when a disk drive has completed the Seek or Drive Reset function (RKDS 06 - RIW IS RDY
set). When a Seek or Drive Reset function has been initiated on the disk drive (Address Acknowledge),
an interrupt request occurs if RKCS 06 (IDE) is set. This process normally requires 1 p,s but may range
up to 3.3 ms, if an attempt is made to abort a Write function. Head movement, however, may take as
long as 80 ms, after which a second interrupt (RKCS 13 - Search Complete) occurs (if IDE is set). In
the interval between these two events, the selected disk drive is busy moving its heads, but the controller is free to perform any RKVll-D function on any other available disk drive. Once a disk drive
has begun moving its head mechanism, only a Drive Reset function can stop it. An attempt to perform
any other function on a disk drive whose heads are in motion results in a hard error condition.
The data transfer functions (Read, Write, Read Check, and Write Check) all begin with an automatic
"implied" Seek. This allows the user of a single disk drive system to ignore the Seek function completely and initiate data transfer functions directly. The hardware poll logic is initiated only for Seek
and Drive Reset functions and not for the "implied" Seek portion of data transfer functions.
3.6 POWER FAIL
An RKVll-D system contains a number of power supplies, each with its own circuitry for detection of
a power failure:
1.
2.
3.

The central processor and other computer-related supplies
The RKVll-D box
The RK05 disk drives.

If the power to the entire system is interrupted, a variety of events can occur depending on which of the
system supplies first senses a power loss, the worst of which is the abortion of the function currently in
process in the RKVll~D. Also, if a Write function was in process at the time of the failure, the sector
being written at the time of the power loss may contain erroneous but readable data. All of the RK05
drives will unload their heads, and no data or format on any disk drive will be lost.
If one or more of the computer-related supplies should malfunction, the program being executed is
interrupted and a power down sequence occurs in the computer. The result is the same as a system
power failure except that the RK05 disk drives do not unload their heads. No data or format on any
disk drive will be lost.

3-11

If the RKVll·D power supply malfunctions, the result is the same as a system power failure except
that the computer and its parts will continue to operate. Because no dc power is available to the
RKVll·D, no interrupt or error condition will occur to notify the computer that a failure has
occurred. In most cases the RKVll·D controls the system disk, and this sort of malfunction would
"hang" the software in the computer. The same unreportable error occurs if any of the computer·
related power supplies has a similar m.alfunction.
An RKVll·D power supply malfunction is easily identified both physically and logically. Physically
the "DC ON" LED on the power supply console will extinguish, and all the disk drives will unload
their heads. Logically, all RKVll·D addressable registers contain all zeros.
If any of the RK05 disk drives senses a loss of ac or dc power, no new functions can be initiated. If an
ac power loss is sensed and a function is in progress, the current sector will finish properly, and the
next sector pulse will unload the heads-setting bit 15 RKER (D RE). If a malfunction occurs and a dc
power loss occurs, the function is aborted; and-if writing-the sector being written may be
logically damaged and in need of reformatting before it can be used again. Bit 15 RKER (DRE) and
bit 12 RKDS (DPL) are set.

3·12

Reader's Comme

RKVII-D Disk Drive Controller
User's Manual
EK-RKVII-OP-OOI

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FIRST CLASS
PERMIT NO. 33
MAYNARD, MASS.
BUSINESS REPLY MAIL
NO POSTAGE STAMP NECESSARY IF MAILED IN THE UNITED STATES
Postage will be paid by:

Digital Equipment Corporation
Technical Documentation Department
Maynard, Massachusetts 01754