Wang System 2200 User manual

WANG 2200
Model 2280/2280N
Disk Diive User Manual

2200
Model 2280/2280N
Disk Drive
User Manual
Copyright ®Wang Laboratories, inc., 1979
700-521 6C
WANG
WANG LABORATORIES, INC., ONE INDUSTRIAL AVENUE, LOWELL, MA 01851 'TEL: [phone]. TWX710-343-S769. TELEX 94-7421

Disclaimer of Warranties
and Limitation of Liabilities
The staff of Wang Laboratories, Inc., has taken due care in preparing
this manual; however, nothing contained herein modifies or alters in any
way the standard terms and conditions of the Wang purchase agreement,
lease agreement, or rental agreement by which this equipment was
acquired, nor increases in any way Wang's liability to the customer. In no
event shall Wang Laboratories, Inc., or its subsidiaries be liable for inci-
dental or consequential damages in connection with or arising from the
use of this manual or any programs contained herein.
Warning: This equipment generates, uses, and can radiate radio fre-
quency energy and, if not installed and used in accordance with the
instructions manual, may cause interference to radio communications. It
has been tested and found to comply with the limits for aClass A
computing device pursuant to Subpart Jof Part 15of FCC Rules, which
are designed to provide reasonable protection against such interference
when operated in acommercial environment. Operation of this equipment
in aresidential area is likely to cause interference in which case the user
at his own expense will be required to take whatever measures may be
required to correct the interference.
WANG
WANG LABORATORIES, INC., ONE INDUSTRIAL AVENUE, LOWELL, MA 01851 •TEL. [phone], TWX 710-343-6769, Telex 94-7421

HOWTO USE THIS MANUAL
This manual provides information concerning the operation of the Model
2280/2280N series disk drives. It is intended to be used in conjunction with
the Wang BASIC-2 Disk Reference Manual .
Chapter 1discusses the concept of information storage and retrieval on
the disk, including an overview of the disk hardware and the principles of
disk operation. Chapter 2provides specific operational data, including
power-on and formatting procedures. Disk drive specifications £uid maintenance
information are collected in the appendices.
Ill

TABLE OF CONTENTS
CHAPTER 1GENERAL INFORMATION
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
CHAPTER 2
2.1
2.2
2.3
2.4
2.5
2.6
2.7
Introduction
The Disk Processing Unit (DPU)
Random Access Data Storage
The Disk Platter
Sectors on the Disk Platter
Track and Sector Numbering on the Disk Platter ..
Disk Access Time
Addressing the Model 2280/2280N
MOUNTING AND FORMATTING INSTRUCTIONS
Unpacking and Inspection
Installation •••
Model 2280/2280N Operating Procedures
Power On Procedure
Controls and Indicators
Loading and Unloading the Removable Disk Platter .
Disk Cartridge Removal
Loading aNew Disk Cartridge
Handling and Storage of the Removable Disk Platter
Model 2280/2280N Formatting Instructions
Error Correcting Code (ECC)
1
4
5
5
6
6
7
8
9
9
11
11
11
12
12
15
17
17
18
APPENDICES
Appendix AModel 2280/2280N Specifications ..
Appendix BDisk Platter Maintenance Information
Appendix CEquipment Guarantee and Prevention
Maintenance Information
INDEX
19
21
24
25
XV

FIGURES
1-1 Model 2280/2280N Disk Drive 1
1-2 Model 2280/2280N Disk Drive Fixed and Removable Platters .... 3
1-3 Model 2280/2280N Disk Unit Read/Write Heads 4
1-4 Concentric Tracks on aDisk Platter with Enlarged View
of Several Tracks Showing How Information Is Stored 5
1-5 Cross-section of aDisk Platter Showing Track Numbering
on the Upper and Lower Surface 6
1-6 Sector Numbering on aModel 2280-1 /2280N-1 Disk Surface 7
2-1 Model 2280/2280N Series System Configuration 10
2-2 Model 2280/2280N Dual System Configuration 10
2-3 The Model 2280/2280N Control Panel 12
2-4 Opening the Access Door 13
2-5 Removing the Disk Cartridge 13
2-6 Locking the Cartridge onto the Dust Cover 14
2-7 Carrying aSealed Cartridge 14
2-8 Loading the Disk Cartridge 16
2-9 The Wrong Way to Load the Disk Cartridge 16
2-10 Closing the Access Door 16

CHAPTER 1
GENERAL INFORMATION
1.1 INTRODUCTION
The Model 2280/2280N series of Fixed/Removable Disk Drives is
specifically designed for the customer who has large data storage
requirements. Each of the Model 2280/2280N series of disk drives contains
approximately 13.4 megabytes of removable storage and up to 67.0 megabytes of
fixed storage, depending upon the model designation. Three versions of the
Model 2280/2280N are available: the 2280-1 (2280N-1) ,the 2280-2 (2280N-2) ,
and the 2280-3 (2280N-3) ,with total storage capacities of approximately 26.8,
53.6, and 80.4 megabytes respectively.
To speed processing and provide extensive error correction, the disk
units are controlled by an intelligent Disk Processing Unit (DPU) which can
support two drives. One DPU is included in the price o£ a2280 disk unit. A
Model 2280N disk drive, identical to aModel 2280 in all other respects, is
shipped without aDPU and is intended for use as the second drive on aDPU.
Up to three 2280 DPU's, with amaximum of two drives each, may be attached to
a2200 system (the 2200T, PCS-II, PCS-III, and WCS-15 excluded).
Figure 1-1. Model 2280/2280N Disk Drive

In a standard configuration (see Figure 2-1) ,one Model 2280 disk drive
is connected to the DPU. The DPU is attached to the 2200 Series Central
Processing Unit (CPU) via astandard Model 22C03 disk controller. In adual
system configuration (see Figure 2-2) ,a2280N disk drive is cabled to the
2280 disk drive, and its output lead is connected to the DPU. Both disk units
may thereby be controlled by the same DPU.
The Model 2280/2280N Disk Drives contain up to four disk platters
mounted horizontally on asingle drive shaft. The platters are mounted one
above the other, somewhat as phonograph records are stacked on arecord
changer (see Figure 1-2) .The top disk platter is housed in acartridge which
can be removed from the disk unit and replaced; it is therefore referred to as
the removable disk platter. Because it is contained in asealed,
cartridge-like casing to protect it from damage when it is removed from the
disk unit, the removable platter is also sometimes referred to as adisk
cartridge. The other three disk platters are positioned below the removable
platter on the shaft. As an integral part of the disk unit, they cannot be
removed, suid are therefore called the fixed disk platters. The shaft itself
is coupled to adrive motor which spins the disk platters at aconstant speed
of 3600 rpm.
Information is recorded on, or read from, the surface of adisk platter
via the read/write head. The read/write heads are attached to acomb-type
access assembly consisting of four access arms (see Figure 1-3) .The
read/write head is fixed in position and cannot move independently of the
access arm.
When adisk statement or commamd is executed from the system CPU, the
access assembly moves the read/write heads in and out over the surface of the
disk platters as they rotate. Aread/write head CcUi then record (write)
information on asurface of adisk platter or retrieve (read) information from
aplatter as the platter rotates past the head's position.
The fixed platters can contain up to five recording surfaces with one
track servo surface; the removable platter contains one surface which is a
recording surface and one which is atrack servo surface. Aservo surface
contains prerecorded information that is used by the drive electronics to
position the read/write heads to the desired track. (The number of recording
surfaces accessible in each Model 2280/2280N disk unit is shown in the
following table.)

Recording Surfaces on the Model 2280/2280N
Model Number of Recording
Surfaces
2280-1 or 2280N-1 1Removable, 1Fixed
2280-2 or 2280N-2 1Removable, 3Fixed
2280-3 or 2280N-3 1Removable, 5Fixed
Removable Disk Platter
Lower Surface
Fixed Disk Platter
Lower Surface
Fixed Disk Platter
Lower Surface
Fixed Disk Platter
Lower Surface
Fixed Disk Platter
Upper Surface
Rxed Disk Platter
Upper Surface
Figure 1-2. Model 2280/2280N Disk Drive Fixed and Removable Platters

Fixed
Disk Platter
Figure 1-3. Model 2280/2280N Disk Unit Read/Write Heads
1.2 THE DISK PROCESSING UNIT
The Disk Processing Unit, included in the price of all 2280 disk drives,
is an intelligent controller/processor enabling two Model 2280/2280N drives to
operate quickly and efficiently. When attached to astandard 2200 disk
controller, this self-contained unit controls data transfer between the disk
platters and the 2200 system CPU. The DPU can thereby handle multi-sector
data buffering, and control read/write, format, copy and verify operations.
The DPU also performs extensive error checking and correction.
By off-loading responsibility for the above tasks from the CPU to the
DPU, overall system performcince has been significantly improved. For example,
the COPY function without the DPU requires approximately five minutes. With
the DPU, this time has been reduced to two minutes. Likewise, the DPU allows
aVERIFY operation to be completed in approximately 25 seconds for a13.4
megabyte disk.
The 2280/2280N disk drive unit can also be given multiplexing capability
with the addition of an optional Model 2280MUX. Using a"star" type
configuration, up to three VP or MVP CPU's an be individually connected to a
2280 DPU. Each CPU may be separated by amaximum of 1000 feet (304.8 m) from
the 2280 DPU, thus allowing for multiple MVP's or VP's to share over 160
megabytes of random access storage.

1.3 RANDOM ACCESS DATA STORAGE
The disk drive provides ahigh volume of random access program and data
storage from which data emd progreuns may be rapidly accessed. Each storage
location on the disk has aunique identification tag or address which can be
directly accessed by the system. Thus, unlike sequential-access storage
devices (such as magnetic tape drives, punched tape, and card readers) ,the
disk does not have to read sequentially through afile in order to locate a
desired item of information. Instead, the disk can skip over all intervening
records and directly access aspecified location for data storage or
retrieval. Hence, random-access devices are also referred to as direct-access
devices
.
Random access capability is very valuable when interrogating or updating
alarge file, since in many cases, the records are not accessed in sequential
order. Even in sequential-processing operations, however, the disk is usually
as fast or faster than most other external storage devices.
1.4 THE DISK PLATTER
The storage medium of all disk units is the disk platter. Adisk
platter is athin, flat, rigid circular plate. It is coated on one or both
sides with amagnetic material, usually iron onide, and except that it has no
apparent grooves, closely resembles aphonograph record. The magnetic iron
oxide on each recording surface is arranged in concentric tracks. Information
is stored on atrack in the form of magnetized spots of iron oxide, much the
same way it is stored on magnetic tape (see Figure 1-4) .Refer to Appendix B
,
Disk Platter Maintenance Information, for acomplete discussion of handling
and storage considerations for disk platters.
II II^VWIM^WWI^WM IIMIIII^I
IIllVyi IWWIMWI lHII II
IllWi y^^ftW IIIII I^IWI^I
#11 INI MIIIHIIWI IIWI^WI
Figure 1-4. Concentric Tracks on aDisk Platter
with Enlarged View of Several Tracks
Showing How Information Is Stored

1.5 SECTORS ON THE DISK PLATTER
In general, it is desirable to be able to store and retrieve information
in units smaller than an entire track. For this reason, each track is divided
into anumber of discrete segments called sectors. Asector is the smallest
discrete unit of storage on the disk and has afixed storage capacity of 256
bytes. Each sector carries its own sector address, and can be directly
accessed by the system. On aModel 2280/2280N disk platter, each track is
divided into 64 sectors.
In addition to the 256 bytes in each sector reserved for data storage,
the disk processing unit records several bytes of control information,
including sector address and an error correcting code (ECC) .The sector
address is, of course, needed to enable the system to uniquely identify and
access each sector. The ECC is used by the system to monitor the integrity of
data stored in the sector and to correct certain types of data recording
errors. All system control information is created, interpreted and maintained
solely by the disk controller and is completely transparent and inaccessible
to the user.
1.6 TRACK AND SECTOR NUMBERING ON THE DISK PLATTER
Track numbering is sequential on each recording surface, starting with
the outermost track which is designated as track #0, and ending with the
innermost track designated as track #822. Atotal of 823 tracks are numbered
independently on each disk surface. Sectors are also numbered independently
on each track and on each surface.
168 822I
m///mmmimmi/m/i/////A
168 822|
822 168
PW/Ji^^^^/^
822 168
Figure 1-5. Cross-section of aDisk Platter Showing Track
Numbering on the Upper and Lower Surface

Track #
1
2
Sector #
-63
64 -127
128 -191
821 52.544 -52.607
822 Not user accessible. Used for alternate
sectors. (See Section 2.6.)
Figure 1-6. Sector Numbering on aModel 2280-1/2280N-1 Disk Surface
1.7 DISK ACCESS TIME
When the disk platter is formatted, the sectors are numbered
sequentially; therefore, when information is read from or written on the disk,
the sector arrangement is sequential. Although it is useful for the
programmer to understand how sectors are arranged within tracks and how the
tracks are identified, the system itself does not recognize tracks as
independent entities. All absolute addressing of data stored on the disk is
done in terms of sector addresses. When presented with asector address, the
system automatically moves to the track which contains that sector. The use
of sector addresses minimizes access time for disk operations.
In order to retrieve apiece of information from the disk, the system
must determine on which disk platter the information is stored and in which
sector (s) on that platter the information is contained. The access arm must
then move the read/write head to the appropriate track and access the
appropriate sector.
There are, therefore, two distinct physical operations which must be
carried out in order to access any particular sector on adisk platter:
1. The access assembly must move in or out to position the read/write
head over the appropriate track on the appropriate platter. This
operation is called the track access.
2. The read/write head must wait for the appropriate sector in the
track to rotate beneath it as the platter revolves. This wait is
known as the disk latency period.
The time required to perform the first of these operations is called the
track access time. The time required to perform the second operation is
called the disk latency time. The track access time is determined by the
number of tracks which must be traversed by the access arm. The average track
access time therefore increases somewhat with the size of the disk
configuration. The disk latency time, on the other hand, is determined solely
by the rotational speed of the disk unit. The time required for each
operation must be included in the total time required to access asector on a
disk platter. Appendix Aprovides timing information on the Model 2280/2280N.

1.8 ADDRESSING TEffi MODEL 2280/2280N
Each Model 2280/2280N contains one removable platter and afixed storage
area which is divided into 1, 3or 5"logical" platters or recording
surfaces. For consistency with other 2200 disk units, "logical" platters or
surfaces are simply referred to as platters.
In aprogram, the user refers to each platter on the Model 2280/2280N
"D" is the device type.
Alternatively, for
with aunique device address of the form /Dup, where
"u" specifies the disk unit and "p" specifies the plat
compatibility with other 2200 disk units, device types 3and Bcan be used
address the 1st fixed platter and the removable platter, respectively. to
Each 2280/2280N unit or pair of units is connected toaDPU which is, in
turn, connected to astandard 2200 disk controller. The controller can be set
to address 10, 20 or 30. The tables below specify the device addresses used
for each controller setting.
If disk controller is set to address 10,
Platter 1st Disk Unit 2nd Disk Unit
removable /DIO (or /BIO) /D50 (or /B50)
1st fixed /Dll (or /310) /D51 (or /350)
2nd "/D12 /D52
3rd "/D13 /D53
4th "/D14 /D54
5th "/D15 /D55
If disk controller is set to address 20,
Platter 1st Disk Unit 2nd Disk Unit
removable /D20 (or /B20) /D60 (or /B60)
1st fixed /D21 (or /320) /D61 (or /361)
2nd "/D22 /D62
3rd "/D23 /D63
4th "/D24 /D64
5th "/D25 /D65
If disk controller is set to address 30,
Platter 1st Disk Unit 2nd Disk Unit
removable /D30 (or /B30) /D70 (or /B70)
1st fixed /D31 (or /330) /D71 (or /370)
2nd "/D32 /D72
3rd "/D33 /D73
4th "/D34 /D74
5th "/D35 /D75
8

CHAPTER 2
MOUNTING AND FORMATTING INSTRUCTIONS
2.1 UNPACKING AND INSPECTION
Because the disk unit is asensitive device, it is packed using special
techniques to protect it from damage in shipping. It should be unpacked and
inspected only by aqualified Wang Service Representative. Failure to follow
this procedure voids the Uang equipment warranty.
2.2 INSTALLATION
The Wang Service Representative will inspect the disk drive for possible
shipping damage, connect it into the system, and turn it on to verify proper
operation.
The following installation procedure should be observed for the disk
unit:
1. Plug the DPU into the disk controller on the 2200 CPU chassis.
2. Plug the 2280 disk drive connector cables into the DPU. After
attaching the cables, secure them with lock clips or screws at the
DPU connection.
3. Asubsequent 2280N disk drive cables to the first drive and to the
DPU.
4. Plug the DPU power cord into agrounded (three-hole) wall outlet.
Input power requirements for the DPU are 115 VAC, 2amps, 50/60 Hz +
1cps (or 220 VAC, 2amps, 50/60 Hz +1cps, by special request).
As the DPU is usually installed within the disk drive cabinet stand,
it is recommended that the DPU power cord be plugged into a
switch-controlled outlet to facilitate powering on and off.
5. Plug the disk drive power cord into agrounded (three-hole) wall
outlet. Input power requirements for the disk are 115 VAC, 9amps,
50/60 Hz +1cps (or 220 VAC, 5amps, 50/60 Hz +1cps, by special
request)
.
6. Plug the system power cord and the electrical power cords of all
other peripherals into grounded wall sockets.

2280
Figure 2-1. Model 2280 System Configuration
2280 2280N
Figure 2-2. Model 2280/2280N Dual System Configuration
Note: If a Model 2280 disk drive is already installed in the
system, it can be field-upgraded to adual drive system by the
purchase and installation of a2280N drive.
10

2.3 MODEL 2280/2280N OPERATING PROCEDURES
Power On Procedure
1. Switch on the DPU power.
2. Be sure that the disk START/ STOP switch is in the STOP position.
(Never power ON or OFF in the START mode.) Note :Each drive in the
dual drive configuration has its own START/STOP switch.
3. Switch ON power for all peripherals, including the disk. On adual
drive, both the master drive and the slave drive have apower switch.
4. Switch ON the main power switch of the CPU. This Master Initializes
the system.
5. Turn the START/ STOP switch to the START position. The READY
indicator begins blinking while the disk is accelerating, and
remains constantly illuminated when the unit is up to speed and the
heads are loaded (after about 60 seconds)
.
6. The disk is now ready to be used or formatted.
NOTE
The disk unit(s) should always be switched off before
powering down the DPU.
Controls and Indicators
me power switch is located on the rear of the Model 2280/2280N.
Switches and indicators on the control panel are described as follows:
Control or Indicator Function
START/ STOP Switch Adual-action switch which energizes the
spindle motor of the disk drive and puts the
disk in operating mode provided the
following conditions are met:
1. The disk drive power switch is ON.
2. The disk cartridge loading door is closed
and latched.
3. The FAULT indicator light is OFF.
11

START Indicator
READY Indicator
When the START/STOP switch is in the START
position, the START indicator illuminates,
and extinguishes when the switch is in the
STOP position.
The READY indicator illuminates continuously
whenever the unit is up to speed, heads are
loaded, and the FAULT indicator light is OFF
(indicating there are no faults within the
unit that require manual intervention) .The
READY light blinks throughout the spindle
start and stop procedure.
FAULT Indicator This indicator illuminates
hardware error (fault) exists. when adisk
WRITE PROTECT
CART Switch This switch, when depressed, disables writing
to the removable disk platter, protecting the
platter from accidental over-writing.
WRITE PROTECT
FIXED Switch This switch, when depressed, disables writing
to the fixed disk platters.
Figure 2-3. The Model 2280/2280N Control Panel
2.4 LOADING AND UNLOADING THE REMOVABLE DISK PLATTER
The Model 2280/2280N disk storage area contains aremovable disk platter
and afixed disk portion. The fixed disk portion is installed at the factory
and cannot be removed from the disk unit. The removable disk platter, as its
name indicates, can be taken out and replaced by the operator. The following
instructions explain how to change the removable disk platter (disk cartridge)
.
Disk Cartridge Removal
Step 1. When the READY indicator is illuminated, depress the START/STOP
switch and wait about 30 seconds for the indicator to extinguish
(the spindle motor has shut off) .(While the READY indicator is
illuminated, the disk cartridge cannot be removed.)
12

step 2. After the READY indicator ceases blinking and extinguishes, open the
disk cartridge access door by pulling back the door handle, and
pressing in on the door release lever inside the handle.
1", -; -,^* ':T^'^^%''^rf^''&^'
,
Figure 2-4. Opening the Access Door
Figure 2-5. Removing the Disk Cartridge
Step 3.
Step 4.
With aslight upward pressure
cartridge out of the receiver. on the cartridge handle, pull the
Turn the dust cover over and set the disk cartridge into it. (The
arrow on the cartridge must be aligned with the arrow on the dust
cover) .Press the cartridge near the handle to lock the dust cover
onto the disk cartridge. Both cover and cartridge can be carried as
aunit by lifting the handle again without touching the cover
release button.
13