Honeywell FocusPRO 6000 Series User manual

Honeywell
SERIES 6000
SUBJECT:
OSS190 AND DSS190B DISK
STORAGE SUBSYSTEM
REFERENCE MANUAL
General Description, Functional Description, and Operating Instructions for the
DSS190 and DSS190B Disk Storage Subsystems.
SPECIAL INSTRUCTIONS:
This manual supersedes the previous edition, Revision 2, dated May 1974. This
edition includes Series 6000 disk storage equipment only. Since the contents of
the manual have been extensively revised, change bars and asterisks have not
been used.
DATE:
. January 1975
ORDER NUMBER:
DB37, Rev. 3

PREFACE
This manual is a reference document providing hardware -oriented dese ripti ve and
instructive material for users of the DSS190 and DSS190B Disk Storage Subsysterrls and for
others concerned with their technical aspects. application, or operation. The basic
difference between DSSl90 and DSSl90B is the use of different disk pack drives. A physical
description of each type of disk pack drive is located in Section 1.
The manual is divided into three sections: Section I contains a general description of
the hardware used in the subsystem. including its performance specifications, capabilities,
and optional features. Section II contains a description of the specific functions performed
by the subsystem, including data formats, instructions, and status conditions. Section III
contains a description of the operator-accessible controls. switches, and indicators, and the
procedures necessary to enable personnel to operate the subsystem.
The following manuals supplement the information contained in this manual:
Series 600/6000 Macro Assembler Program (GMAP), Order Number BN86
Series 600/6000 DATANET 355 Communications Processor, Order Number BS03
Series 6000 System Startup and Operation, Order Number DA06
Series 6000 Equipment Operator's Manual. Order Number DA33
©1972, 1973, 1974, 1975, Honeywell Information Systems Inc.
File No.: 1703
DB37

Section I
Section II
CONTENTS
General Description ••••••••.••••••••••••.•••.•..••••.•.•
Subsystem Configuration ••..••••••••••.•.•..•.••.•••••
Subsystem Components ••••.•••••••..•••••.••.•••.••••.
Disk Storage Control (DSC) . . • • . . • • • ••.••••••
Disk Pack Drives . • • . • . • • • . • • • • • . • . • .••••••••
Disk Pack ......•.........•......•.......
Functional Description
Component Functions
Link Adapter (LA)
Disk Storage Control (DSC)
Disk Control Adapter (DCA) •..•••••••.•.••••.•••••••
Disk Storage Unit (DSU) •.••.••....••.••....•..••••.•
Disk Pack ..........•..........................
Basic T rack Format ••..•.•..•••••••••.••••••.
Disk Pack Capacity ••....••• • •••.•...••..•••.••
Increased Capacity Format (ICF) •.••••.•••.•.••.•
Instruction Set ••••••..••••.•....•••..•....••••....
Instructions
Seek
Special Seek •••••.•••••.••..
Preseek
Restore
Read
Read ASCII
Write
Write
ASCII
Write and Compare ••..•••••.....•.•.••••••.•.•••
Read Nonstandard Size Sector •.•.•••..•..•••..
Read Track Header ••...•.•••••.•.•..•••••.•.
Format Track
Request Status
Reset Status
Write Control Register
Read Control Register
Read Status Register
Release •..•.•...••
Read EDAC Register
Reserve Device •..••••••••.•..•.•
Set Standby •.....•.....•..•....•......•....•••••
Bootload Control Store ••••••••.••••••••••••••••••
ITR Boot •.•....•.......•.......•....•..•.....•..
Execute Device ••••••.••••••••••.••••.••..•••••••
Execute Microcoded Device (MD) Routine •••••••••.
Write Control Main Memory. Binary or ASCII ••••••
Read Control Main Memory. Binary or ASCII ••••••
Conditional Write Lock Byte. Write Lock Byte •.••••
iii
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1-5
2-1
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2-4
2-4
2-4
2-4
2-5
2-6
2-7
2-10.1
2-11
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2-13
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DB37

Section II (cont)
CONTENTS (cont)
Read Lock B-yte ••.•.•.•.•...•.•.....•.........
Suspend Control ••.•••.•.•...••........••......
Release Control •••••••••••••••••••••••••••••••
Send Special Interrupt ••••••••••••••••••••••••••
Read Logical Channel Number ••••••••••••••••••••
Major Status and Substatus ......................... .
Cha.nn~l Ready •••••••••••••••••••••••••••••••.•
No Substa tus •••••••••••••••••
Retries
.....................
Device in T&D Mode ••••••••
Data Corrected ••••••••••••
Device Busy ••••••••••••••••••
Device P~sitionin.g •••••••••
Alternate' Channel in Control
Attention ........................ .
Write lr1hibit ..................................... .
Seek Incomplete ................................... .
Device Inoperable .................................. .
Device in Standby ............................... .
Device Offline ............................... .
Data Alert •••••.•••••••.•.••..............•.•..
Transfer Timing Ale rt •••••••••••••••••••••••
Trans~ssion Parity Alert •••••••••••••••
Invalid Seek Address ......................... .
Heade r Verification Failure •••••••••••••••••••
Check Character Alert ........................ .
COnlpare Alert •••••••••••••••
End of File •••••••••••••••••••••
Good Track Detected •••••••••••••••••••••••••
Last Consecutive Block
......................
Block Count .L.inrit •••••••••••••••••••••••••••
Defective Track Detected, Alternate Assigned ••
Defective Track Detected, NoAlternateAssigned.
A1te rnate Track Detected •••••••••••••••••••••
lr1struction Rejected •••••••••••••••••••••••••••
Invalid Ope ration Code •••••••••••••••••
Invalid Device Code •••••••• • ••••••••••••••
Parity Aiert on IDCW ••••••• • ........ .
Invalid Instruction Sequence •••••••••
MPC Device Attention ••••••••••••••••••••••••••
Configura tion E rro r .......................... .
Multiple Device s ............................. .
Device Number Error •••••••••••••••••••••••
CA Error ••••••••••••.•.•••..•..•.••.••••.•.
Alert EN-l
CA EN-l Error
.............................
CA Ale rt No EN -1 •••••••••••••••••••••••••••
MPC Device I>ata Alert •••••••••••••••••••••••••
Transmission f>arity Error ••••••••••••••••••
Inconsistent Command •••••••••••••••••••••••
Checksum Error ••••••••••••••••••••••••••••
Byte !..ockout •••••••••• ;. •••••••••••••••••••••
EDAC f>arity Error •••••••••••••••••••••••••
Sector Size Error •••••••••••••••••••••••••••
Nonstandard Sector Size
Search Alert "First Search" ••••••••••••••••••
Cyclic Code Error "Not First Search" •••••••••
iv
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DB37

Section II (cont)
Section III
CONTENTS (cont)
Search Alert IINot First Search"
Sync Byte Error •.••••••••••
Alternate Track Error •••••••
EDAC Correction Last Sector
EDAC Correction
EDAC Correction
Not Last Sector
Block Count Limit
EDAC Uncorrectable •• " • " • " . " • " • " " • " " " " •••••
EDAC Correction - Short Block • " " ••• " • "• " " " •
MPC Command Reject ••• " " ••• " " •••••• " " " • " • " • " •
Illegal Procedure •••• " " • " " ••••••• " ••• " ••••••
illegal Logical Channel Number ••••••• " " " •••••
illegal Suspend • " " " " " •••• " " ••• " • " •• " • " " " "
Continue Bit Not Set ••• " •• " " " •• " • " • " " " • " •
Operating Instructions • " " .••• " •• " " •••• " " •••• " " " ••••
Subsystem Considerations • " •• " •••• " " • " •••• " • " " " •••• " •
Subsystem Controls and Indicators .""."""""""""""",,
DSC Operating Controls and Indicators •• " • " " • " ."
AC Breaker On •.•. " ... """""."""""""""""""""""""
Power On """. """. ". "". """• """""". """""""""""""
Powe r Off """"""""". """""""""""""""""""""""""""
Norrn.al/Test •............•.... " ..•.•......
Ready/Trouble ."." •• """.""." •••• ,,"",,.,,""""
Over Temp/Alarm Reset ••• ". "" " ".,," " ".,," "" ." ••
Start "". " .. ". ". ". """""". ". """ ... " ... ". """"
Automatic /Manual
Int/Ext/Cont Store
Operator Interrupt
Halted ••••••..••. " .••.•
Initialize """"" ... """. "". ". """. """"" .. ""
Addres s /Simulate •• " .• " •••••••.•.•••••••.••••••
Control Configuration Switches ••• " •••••••.•••••••••
DSU 190 Operating Controls and Indicators ••••.••
DSU 190B Operating Controls and Indicators ••••••
Subsystem Operation ••••• " •••••.•. " •••• " ..••.•••••
DSC Operation . "". ". " .. """"". "". """". ". """""
DSU Operation "" .. """""."."""""""."""."""" .. """.""
DSU 190 Initialization • • • • • • • • . . .•••••
DSU 190 Disk Pack Installation ••••.•••••.•.
DSU 190 Disk Pack Removal
DSU 190B Initialization
DSU 190B Disk Pack Installation ••••.•• " .
DS U 190B Disk Pack Removal •••••••.••••••.••.•.
Emergency Operation
Subsystem Maintenance
DSC IDS U Maintenance
" " "." " " " ." " .. " " " ." ... " ." " " " ".
Disk Pack Maintenance
Handling the Disk Pack
Storing the Disk Pack
v
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3-1
3-1
3-2
3-2
3-3
3-3
3-3
3-4
3-4
3-4
3-4
3-4
3-4
3-5
3-5
3-5
3-5
3-5
3-5.2
3-5.2
3-7
3-8
3-8
3-8
3-8
3-9
3-9
3-10
3-10
3-11
3-11
3-11
3-11
3-11
3-12
7/78
DB37A
*

Figure
I-I.
Figure
1-2.
Figure
1-3.
Figure 1-4.
Figure 1-5.
Figure
1-6A.
Figure 1-6B.
Figure 1-7.
Figure 2-1.
Figure 2-2.
Figure
2- 3.
Figure
2-4.
Figure 2-5.
Figure 2-6.
Figure 2-7.
Figure
2-8.
Figure
2-9.
Figure 2-10A.
Figure 2-10B.
Figure 2-10C.
Figure 2-10D.
Figure
2-11.
Figure 2-12.
Figure 2-13.
Figure 2-14.
Figure
3-1.
Figure 3-2.
Figure 3- 3.
Figure 3-4.
Figure 3-5.
Table 2-1
Table 2-2.
Table 2- 3.
Table 2-4.
Table 2-5.
Table 3-1.
Table 3-2.
Table 3-3.
ILLUSTRATIONS
Basic Subsystem •..•.........••.••. ""• " ..•.•. " •• " •.•• ".
16-Device Subsystem •••••••••••••••••••••••••••••••••••
Dual Control Subsystem ••••••••••••••••••.••••••••••••••
Dual Subsystem with Four Simultaneous Channels •••••••••
Disk Storage Control (DSC) •••••.••••••••••••••••••••••••
Disk Pack Drive DS U 190 ••••.•••••.••••....•••.•.•••••••
Disk Pack Drive DSU190B
Disk Pack •.•...•.••..•. "_ •..•. " .. " .•... " .• """"• """""•
DSS 190 or DSS 190B with Six Additional Devices and a
Switched Channel "". "". """". """"" •• """"""""""""""""• ""
DSS 190 or DSS 190B with 14 Additional Devices and Two
Simultaneous Channels •••••••••••••••••••••••••••••••••
Dual Control (Two Single Channels) Crossbarred
Subsystem. (DCX) """". """" .• ""• """• """""""""""""""""""
Two Control Dual Channel Crossbarred Subsystem. •••••••••
Disk Pack Recording Surfaces •••••••••••••••••••••••••••
Basic Track Form.at
Home Addres s Field
RO Field
Rl Field
." ." " " " " " ... " .. " ." " ." " " " ." ." ~ " " " " ." .. " ." ." " " ..
Increased Capacity Format (ICF) •••••••••••••..•••••••.•
CO Count Field """"• " •. "" .• """" •. ". "". " .• """ ... " .. "". ""
Data Fields """"". " .. " ... " .. " •.. " ........ " .... ". """ •..•
eN Count Field ..•... "" ...... ". " .•.•.•........ """ ....•.
Seek Instruction Format
Track Header Format
Format Track Data Format ••.•••••••••••••..•...•..••••
Read Control Register Format •••••••••.••••••••..••••••
DSC Operating Controls and Indicators (Freestanding
C ontr 01) •.•••••••.•••• " ••••••.•• " • " • " •••.• " •.• " .•••••
Operating Controls and Indicators (Control Integrated
in reU) •.•.•••...•...•••••.•........••.•..•.•..•..•••
Control Configuration Switches ••..•.•••.•••.•.••..•••.••
DSU 190 Operating Control and Indicators •••.••••••.••••••
DSU 190B Operating Controls and Indicators •.•.•••.••.••••
TABLES
Functional Characteri,stic:s of the Disk Storage Unit •.•••.••
Disk Pack Capacity (Basic Track Format) ••••••••.••.••••••
Instruction Set .............................••..........
Special Instruction Set •••.••••••••••..•...•.••••••••••••
Major Status and Substatus Codes ••••.••••••.••••••.•••••
Control Configuration Switches •••••••••••••••..•••..•.••
DSU 190 Controls and Indicators •••••••••••••••.••••.•••••
DS U 190B Controls and Indicators •.••.••••••..•••••••.•••
vi
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2-2
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2-3
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2-10.1
2-10.2
2-10.3
2-10.4
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3-3
3-3
3-5. 1
3-5.2
3-5.2
2-5
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2-19
3-5. 1
3-5.2
3-7
DB37

SECTION I
GENERAL DESCRIPTION
The Type DSSI90 and Type DSSI90B Disk Storage Subsystems are high-capacity disk
storage subsystems with advanced microprogramm.ed control and operating features that im-
prove time and throughput. This subsystem provides fast access and large capacity storage for
remote access, multiprocessing, and time sharing in m.edium to large data base systems.
SUBSYSTEM CONFIGURATION
The basic subsystem consists of a disk storage control (DSC) and two disk pack drives
using removable and interchangeable disk packs (see Figure 1-1). Storage capacity is
117,903,360 six-bit characters or 78,602,240 eight-bit bytes per disk pack (or 91,375,104
six-bit characters or 68, 531,328 eight-bit bytes using a basic: track format). This capacity
can be expanded by the addition of up to 16 devices (see Figure 1-2), or 32 devices for
maximtim online capacity using a single or dual subsystem (see Figure 1-3). Figure 1-4
presents a further expansion making use of a dual control subsystem with four simultaneous
channels.
Da
Cha
ta
-
nne!
Da
Cha
ta
-
nnel
Disk Pack Drive s with
DSC Removable Disk Packs
-0 0
1 2
Figure 1-1. Basic Subsystem
DSC Disk Pack Drives with Removable Disk Packs
-0 0 0
------ 0
1 2 3 16
Figure 1-2. 16 -Device Subsystem
I -1
DB37

DSC Disk Pack Drives with Removable Disk Packs
Da ta
0 0 0
-
~
-
-
annel
Ch
------ 0
~-
1 2 3 16
DSC
l-
ta
0 0 0
-
...
--
~
annel
Da
------ 0
Ch
1 2 3
Figure 1 .. 3. Dual Control Subsystem
NOTE:
Data
Channel
LA
DSC
LA - Link Adapter
Data
Channel
LA
DSC - Disk Storage Control
DCA - Disk Control Adapter
Data
Channel
LA
DSC
Data
Channel
LA
Figure 1-4. Dual Subsystem with Four Simultaneous Channels
1-2
16
DB37

Subsystem.s can be easily upgraded in the field by adding the various optional com.-
ponents available. This modularity makes it possible to provide backup com.ponents for
every module in the subsystem. with a maximum of versatility.
SUBSYSTEM COMPONENTS
Disk Storage Control (DSC)
The DSC is a general purpose microinstruction processor housed in a single low-profile
cabinet with an easily accessible operator panel (see Figure 1-5), or in the Integrated Control
Unit (ICU). The modular design of the DSC allows expansion and enhar ... cement of basic sub-
system capacity simply by installing optional hardware.
In addition to the operator panel, the DSC includes:
• A maintenance/configuration panel
• Forced-air cabinet cooling system
• Power supply and power control modules
• A basic disk channel with a link adapter interface to the external user
system (EUS)
• An Additional Drive Electronics, ADEI90. with a disk interface to the
disk pack drives. The disk interface can connect up to four disk pack
drives to the DSC
PHYSICAL SPECIFICATIONS
Dimensions
51 in. high
55 in. wide
28 in. deep
Installed Weight
500lb
Square Footage (including door swing)
30. 5 sq. ft
OPERATING ENVIRONMENT
Temperature
Humidity
50
0 -
100
0 F
(l00 - 38°C)
10% - 850/0
POWER REQUIREMENTS
120/208 V, 60 Hz
1. 83 kVA
AIR CONDITIONING
4650 Btu/hr
Figure 1 -5. Disk Storage Control (DSC)
I -3
DB3?

Options to the DSC include:
• A Dual Simultaneous Channel, DCH190 and DCB} 90B, consisting of one
basic disk channel, one Additional Drive Electronics (ADE190 and
ADE190B) and one data recovery module, for dual-channel crossbar
operation in which data can be transferred between the DSC and two
disk pack drives simultaneously.
• An Additional Data Channel, ADC190 and ADCI90B, provides a second
link adapter interface to the external user system (EUS) for transferring
data between the DSC and EUS on both interfaces, but not simultaneously.
One ADC 190 or ADC 190B may be applied to the DSC and one to the
optional Dual Simultaneous Channel, DCHl90 or DCHI90B.
• For two controls with single channels, a Dual Control Crossbar,
DCXl90 and DCXI 90B, and a disk Control Adapte r, CCA 190 and CCAl90B,
are required to provide crossbarring to all drives.
• For two controls with dual channels, DCH190 and DCH190B, crossbarring
is provided to all drives. (DCXI90 or DCXl90B is not required. )
Disk Pack Drives
The disk pack drive used by the subsystem is either the DSU190 or the compatible
DSU190B Disk Storage Unit. The DSU190 (Figure 1-6A) is an electromechanical disk pack
drive with a single mounting spindle housed in a low-profile cabinet. The DSU190B
(Figure 1-6B) is a single-spindle, moving-head disk pack drive, with associated Device
Oriented Electronics (DOE) housed in a single low-profile cabinet. Both disk pack drives
include easily accessible chambers for mounting the disk pack and convenient operator
control panels.
PHYSICAL SPECIFICATIONS
Dimensions
38 in. high
22 in. wide
49 in. deep
Installed Weight
700lb
Square Footage (including door swing)
12 sq, ft
OPERATING ENVIRONMENT
TeInperature
HUInidity
60
0 -
90
0 F (150 -
32
0
C)
20% - 80%
POWER REQUIREMENTS
208 V, 60 Hz/220 V, 50 Hz
1. 5 kVA
AIR CONDITIONING
4425 Btu/hr
Figure I -6A. Disk Pack Drive (DSU 190)
1-4
DB37

PHYSICAL SPECIFIC A TIONS
Dimensions
42.25 in. high
35 in. wide
30 in. deep
Installed Weight
8501b
Square Footage
15 sq ft
OPERATING ENVIRONMENT
Temperature
Humidity
60
0 _
90
0 F
(15
0 -
32
0
C)
20% - 800/0
POWER REQUIREMENTS
208 V, 60 Hz
2.0 kVA
Figure 1 -6B. Disk Pack Drive DSU190B
In addition to the disk pack chamber and operator control panel, the disk pack drive
includes:
• The disk pack rotating mechanism
• The mechanism that positions the read/write heads with respect to
the disk recording surfaces
• The brush mechanism that cleans the disk recording surfaces during
each power-up sequence
• Two ports that permit the disk pack drive to be connected for siInultaneous
dual-channel crossbar operation
• Direct current power supplies and power supply controls
Disk Pack
The Disk Storage Subsystem uses an M4050 Disk Pack or an equivalent removable disk
pack (see Figure 1 -7). The disk pack includes ten 14-inch storage disks and two protective
disks mounted on a common hub, and an easy-to-handle plastic carrying storage case.
The disk pack can be removed conveniently for offline storage, and may be remounted
readily for online processing.
1 -5 DB37

PHYSICAL SPECIFICATIONS
Disk Dimensions
14 in. diamete r
Number of Disks
lZ Storage Disks (spaced O. 3 in.
apart on a common hub)
Z protective disks (on same hub)
Number of Storage Surfaces
19 Data
1 Servo
Weight
20 Ib (with carrying case)
OPERATING ENVIRONMENT
Temperature
Humidity
STORAGE CAPACITY
1 SO -320 C
200/0 -80%
91,375,104 six-bit characters
68, 531, 328 eight-bit characters
Figure 1 -7. Disk Pack
1-6
DB37

COMPONENT FUNCTIONS
SECTION II
FUNCTIONAL DESCRIPTION
The Disk Storage Subsystem may be configured in many different ways to obtain data
availability and throughput requirements. Versatility, especially adaptability to new require-
ments' is significantly inc reased by the use of a microprogrammed peripheral control as the
disk storage control (DSC) for the subsystem. The disk storage units (disk pack drives and
disk packs) communicate with the DSC across a radial interface that permits a DSU to be
reInoved from service without interfering with the operation of other DSU's in the subsystem.
Four of various subsystem configurations that may be used in a computer system are
shown in Figures 2 -1 through 2 -4. The abbreviations used are:
ADE - Additional Drive Electronics
CCA or CA - Control Adapter
DCA Disk Control Adapter
DCX Dual Control Crossbar (includes associated cables and
additional EDE electronics)
DSC - Disk Storage Control (refers to the complete control)
DSS Disk Storage Subsystem
DSU Disk Storage Unit (refers to the DSU190 and DSU190B
Disk Storage Units unless noted otherwise)
EDAC Error Detection and Correction
EDE Extended Drive Electronics
EUS External User System (refers to any Series 6000 Central
System or DATANET 355 Front-End Network Processor)
IDCW - Instruction Data Control Word
LA - Link Adapter
OPl - Operational In (a status line from the device to the controller
indicating the operational status of the device)
Z -1
DB37

EUS EUS
DBC
Figure Z -1. DSS190 or DSS190B with Six Additional
Devices and a Switched Channel
EUS EUS
LA. LA
DSC
Figure 2-2. DSS190 or DSSI90~ with 14 Additional
Devices and Two Simultaneous Channels
2-2
. DB37

1
1
r------------,
I EUS I
L--__ _ __ 1
LA
LA
DSC
DSC
DCA
CCA
a
DCA
CCA
a
ADEa'EDE
ADE/EDE
ADEa'EDE
8 17
24
9
16
2')
32
DSS 190 or DSS 190B
DSS190 or DSS190B
aRequired with 17 or more drives
Figure 2 -3. Dual Control (Two Single Channels)
Crossbarred Subsystem (DCX)
r------- --,
I IOM-A I
L... --- ....,.-0.=
r---------,
I IOM-B I
1-- ______ ...J
LA
LA
DSC
DSC
DCA
DCA
DCA
DCA
ADE/EDE ADE/EDE
8 17
24
9
16
25
DSS190 or DSS190B
DSS 190 or DSS 190B
Figure 2 -4. Two Control Dual Channel Crossbarred Subsystem
2-3
32
DB37

Link Adapter (LA)
The LA connects the DSC to the EUS as shown in Figure 2 -1 through 2 -4. Each LA has
two ports, providing the ability for the LA to be shared by two physical interface channels for
nonsimultaneous transfer of data between the EUS and the DSC. Channel switching is con-
trolled by the DSC rnicroprogranlS.
Disk Storage Control (DSC)
The DSC is a general purpose, register-to-register microinstruction processor th~t
performs the control functions fOr the subsystem. The DSC accepts macro inst1"uctions from
the EUS and issues the necessary machine instructions to the DSU's via the DCA. The DSC
also obtains status from the DSU's and returns the appropriate status to the EUS. Four
ports are provided in the DSC for connecting as many as two LA's and two DCA's.
Disk Control Adapter(DCA)
The DCA connects the DSC to the DSU's through the Additional Drive Electronics
(ADE/ EDE) as shown in Figures 2 -1 th: .... ough Z -4. The DCA synchronizes, buffers, and
converts information to be transferred between the DSC and the DSU's. Information is
transferred by the DCA to or from only one DSU at a time. Two independent DCA's each
can transfer information to or from different DSU's simultaneously.
Disk Storage Unit (DSU)
The DSU is a disk pack drive capable of reading from or writing in bit serial form on
any of the tracks of a 19-recording surface, 411-track removable disk pack. To be inter-
changeable, all disk packs must be aligned with the same master alignment pack. Two
channels in the DSU permit the DSU to be connected to two DCA's for simultaneous data
transfer operations between the DSU and the EUS. DSU functional characteristics are
listed in Table 2 -1.
2 -4
DB37

Table 2 -1. Functional Characteristics of the Disk Storage Unit
Characteristic Description
Removable Disk Pack
Spindle Rotation
Disk Latency Time
Heads
R/W Heads
Loading Mechanism
Servo Heads
Recording
Mode
Data Rate
Density - outer track
Density - inner track
Head Positioning Times
a
(Track -to - Track)
M4050 (or equivalent)
3600 rpm
8.3 ms (average)
16.7 ms (maximum)
19
Ramp
I
Modified Frequency Modulation (MFM)
806,000 bytes per second
2684 bpi
4040 bpi
55 ms (maximurn)
30 ms (average)
10 ms (minimurn)
a
Does
not include disk latency time or time to read data. Average head
selection time =6 IJ. s
Disk Pack
The disk pack used with the DSU is a removable, interchangeable disk with 19 magnetic
recording surfaces numbered 0 - 18 (see Figure 2 -5). Each recording surface has 411
concentric tracks for a maximum total of 7809 tracks. The tracks on each recording surface
are numbered 000 - 410, track number 410 being the innermost. A group of 19 tracks
(tracks with the same number for each of the 19 recording surfaces) constitutes a cylinder.
i. e., tracks numbered 001 for each of the 19 recording surfaces comprise cylinder 001.
So, there are 411 cylinders for each disk pack. Cylinders 000 through 409 (7790 tracks) are
allocated to user data, system labels, catalogs, alternate tracks, and other information:
cylinder 410 (19 tracks) is reserved for T & D use only. Of the 410 cylinders available,
404 cylinders are addressable, three cylinders are reserved as aiternate cylinders. and
three additional cylinders are addressable to offset any tracks that are deallocated.
2 -5
DB37

BASIC TRACK FORMAT
The basic track forxnat contains a home address area, a track descriptor sector, and
from one to 31 user data sectors per track as shown in Figure 2 -6. Portions of the track
format are described in more detail in Figures 2-7, 2-8, and 2-9 (cross-referenced in
Figure 2 -6).
• Home Address Field - Figure 2-7
• RO Field - Figure 2-8
• RI Field - Figure 2-9
Figure 2 -5. Disk Pack Recording Surfaces
2 -6
DB37

·-
INDEX
GAP 1
IIOME
GAP Z
POINT
92 BYTES
ADDRESS
498YT.f;S
7 f 7 I-;(:C BYTES
T
y
See Fi~ure Z -7
RO DATA
GAP 3
Rt COUNT
8 + 7 ECC BYTES
59 BYTES
) 1 + 7 ECC BYTES
MINIMUM
\.
See Figure 2-9
~------~:~------~~----~~------~
GAP 3
LAST RECORD DATA
GAP 4 INDEX
POINT
~ ____ ~;~ ________ L- ______ ~ ________ ~
----
RO COUNT
GAPZ
II
• 7 ECC AYTES
49 BYTES
-y
See Figure 2 -8 -
GAPZ
Rl DATA
49 BYTES
288 + 7 ECC aYTES
J
Figure 2 -6. Basic Track Format
DISK PACK CAPACITY
The storage capacity of a disk pack and of the track format are shown in Table 2 -2.
Capacity measurements include lengths of fields measured in bytes (8 bits), in words
(36 bits), and characters (6 bits).
Table 2 -2. Disk Pack Capacity (Basic Track Format)
Bytes / Sector /
Bytes / Words /
288-Byte
;Bytes/Disk Pack
Formatted
Sector
Track Track Sector
Fields /Track
X 10
6
Characters I
Disk Packs
X 10
6
288
31
8928
64
31
68.5
91. 3 a
a
Based on 404 cylinders
2-7 DB37

N
I
00
t1
OJ
w
~
(\0 BYTES i:EROS
\" )
r=x=\
HOME ADDRESS
7 + 7 Eec BYTES
GAP
1 • PRECEDES ALL HOME ADDRESSES
2. ZEROS USED TO SYNC PtO
3. DECODING HEX 19 SYNC BYTE
INDICATES PLO SYNC AND THE
BEGINNING OF DATA.
~
(~--------------------H-OM-E--A-DD-R-E~SS'F-I-E-L-D----------------------~~
HOME ADDRESS FIELD
1. DESCRIBES THE CO~DITIO!\ OF nns TRACK.
2. CONTAINS TIlE PHYSICAL ADDRESS OF TIns TRACK.
Pol T u-:. = %ERO
BIT 5 = CE PACK
BITS b-7:
(III :;(lR~IAr. l!V\CK
n1 ALlEle,/UI: mACK
I" :;J.FI:n IVE TRAcr:
11 ilLFECII\T H,\CI\
IWTJ. I C();iTE~'fS
o i.llN llRllER Ci'L I !\lJ~;K tll·.AII
BITS 0-7
(l ZERO
1 ; HIGH ORDER CYLI:-<DER AIJDRESS
:! = ZERO
3-7 = HEAD ADDRESS
Figure 2- 7. Home Address Field
(0 - 41(,)
i BYTES l'SED Fl)R ERR\·R
DETECTION AXD CORREcnox
(0 - 16)