Adaptec ACB-2370 User manual

adaptec
ACB-2370/ACB-2372
User's Manual

COPYRIGHT
©
Copyright 1987, 1988 Adaptec, Inc. All rights reserved.
No
part
of
this publication may be reproduced, stored in a retrieval system,
or
transmitted,
inanyform
or
by
anymeans,electronic,mechanical,photocopying,recording,
or
otherwise,
without the prior written consent
of
Adaptec, Inc., 691 South Milpitas Blvd., Milpitas,
California 95035.
TRADEMARKS
The trademarksreferred to in this manual are identified
and
acknowledgedas follows: IBM
PC/AT, PC-DOS, and OS/2 are registered trademarks
of
International Business Machines
Corporation. MS-DOS is a registered trademark
of
Microsoft Corporation. Unix is a
registered trademark
of
AT
& T. Xenix is a registered trademark
of
Intel Corporation.
Net
Ware
is a registered trademark
of
Novell Corporation.
CHANGES
The material
in
this manual is for information only
and
is subject to change without notice.
Adaptec reserves the right to make changes in the product design without reservation and
without notification to its users.
Additional information may
be
obtained from:
Adaptec, Inc.
Literature Department
691 South Milpitas Blvd.
Milpitas,
CA
95035
FCC COMPLIANCE
This equipment generates and uses radio frequency and
if
not installed and used properly, that
is, instrict accordance with the manufacturer's instructions, may cause interference
to
radio and
television reception. It has been type tested and found to comply with the limits for a Class B
computing device
in
accordance with the specifications inSubpart
J
of
Part 15
of
FCC Rules,
which are designed
to
provide reasonable protection against such interference in a residential
installation. However, there is no guarantee that interference will notoccur in a particularinstal-
lation.
If
this equipmentdoes cause interference to radio
or
television reception, which can be
determined by turning the equipment
off
and on, the user is encouraged to
try
to
correct the
interference
by
one ormore
of
the following measures:
Reorient the receiving antenna.
Relocate the computer with respect to the receiver.
Move the computer away from the receiver.
Plug the computerinto a differentoutletso thatcomputer and receiver are
OI'I.
different
branch circuits.
If
necessary, the user shouldconsult the dealer
or
an experiencedradio/television technician for
additional suggestions. The usermay find the following booklet prepared by the Federal Com-
munications Commission helpful:
"How to Identify andResolve Radio-'IVInterference Problems"
This booklet is available from the U.S. Government Printing Office, Washington, DC 20402,
Stock No. 004-000-00345-4.

Table of Contents
Section
Page
1.0 INIRODUCTION
1-1
1.1
Scope and Purpose of Manual 1-1
1.2 Reference Documents
1-1
1.3 Overview
of Product 1-1
1.4 Hardware and SoftwareRequirements 1-4
2.0 HARDWARE INSTALLATION 2-1
2.1 Introduction 2-1
2.2
Environmental Requirements 2-1
2.3 Unpacking Procedure 2-1
2.4 ACB-2372 Board Layout 2-2
2.5 ACB-2370 BoardLayout 2-3
2.6 System Requirements 2-4
2.7 Integration Into the System 2-6
3.0
SOFIW ARE INSTALLATION 3-1
3.1 Introduction 3-1
3.2 Software Installation Flowchart 3-1
3.3 FormatProcedure for a Single Hard Disk Drive 3-7
4.0
1ROUBLESHOOTING 4-1
4.1 Introduction 4-1
4.2
Adaptec ACB-237X Troubleshooting Checklist 4-2
4.3 Controller Error Codes 4-3
4.4 BIOS Error Codes 4-7
5.0
APPENDICES
A-1
I. Installing SCO Xexix A-1
II. Installing ISC UNIX A-2
III. Installing OS/2 A-3
IV. Installing Novell 2.0A A-5
v. Installing Novell 2.1 A-7
VI. Adaptec Autoconfiguration A-10
VII. Driver and Operating System Support A-12
VIII.
Using More Than 1024 Cylinders A-14
adaptec

Table of Contents
LIST OF TABLES
Table Page
2-1 ACB-237X System Memory Map 2-4
2-2 ACB-2372 ControllerPowerRequirements 2-5
2-3 ACB-2370 ControllerPower Requirements 2-5
2-4 ACB-2372 ControllerJumper Definitions 2-6
2-5 ACB-2370 ControllerJumper Definitions 2-8
2-6 ACB-2372 Controller Connector Definitions 2-15
2-7 ACB-2370 Controller Connector Definitions 2-15
4-1 Class 00 Error Codes (Drive Errors) 4-4
4-2 Class 01 Error Codes (Data Recovery Errors) 4-5
4-3 Class
02 Error Codes (System-Related Errors) 4-6
4-4 Class 03 Error Codes (Diagnostics Errors) 4-6
4-5 Class 04 Error Codes (Timeouts and Misc. Errors) 4-7
4-6 BIOS Error Codes 4-7
LIST OF FIGURES
Figure
Page
2-1 ACB-2372 BoardLayout 2-2
2-2 ACB-2370 BoardLayout 2-3
2-3 ACB-2372 Controllerand Drive Cabling-Twisted
Cable (Hard Disk Cables) 2-11
2-4 ACB-2372 Controller and Drive Cabling-Flat Cable
(Hard Disk Cables) 2-12
2-5 ACB-2370 Controllerand Drive Cabling-Twisted
Cable (Hard Disk Cables) 2-13
2-6 ACB-2370 Controller and Drive Cabling-Flat Cable
(Hard Disk Cables) 2-14
ACB-237X
ii

Section One
Introduction
1.1
SCOPE AND
PURPOSE
OF
MANUAL
The
purpose
of
this manual
is
to
guide
the system
integrator
through
a
successful installation
of
Adaptec's
ACB-237X
board.
This
includes
both
hardware and software installation,
as
well as basic troubleshooting information.
1.
2
REFERENCE
DOCUMENTS
IBM
PC
AT Guide to Operations Manual
IBM DOS Reference Manual Version 3.0 or Higher
IBM
PC
AT
Technical Reference Manual
Appropriate Disk Drive User's Manual
1.3
OVERVIEW
OF
PRODUCT
The
Adaptec ACB-2372 is a high-performance 2,7
RLL
Hard Disk
and
Floppy
Disk
Controller for the IBM
PC
AT
and equivalent personal computers.
The
ACB-2370 is a 2,7
RLL
Hard Disk Controller. The ACB-237X controllers are
software
and
hardware compatible with the
IBM
PC
AT
hard disk controller
interface.
The
Adaptec ACB-2372 2,7
RLL
Hard Disk
and
Floppy
Disk
Controller
and
ACB-2370 Hard Disk Controller have the following features:
IBM hardware compatible.
Plugs directly into
AT
bus compatible systems
without modification. Register (port) compatible to the IBM
AT
controller,
giving true compatibility.
IBM software compatible.
Runs all software, without change, that runs on
the IBM AT controller. Runs software that communicates through the
AT
system BIOS
or
directly to the controller registers, thus, the highest
AT
compatibility is achieved.
1 - 1
adaptec

Section One
Supports two 2,7 run-length limited (RLL) qualified ST-4121506 drives.
Runs High Performance 7 .5 MHz RLL drives from all major RLL
manufacturers. Supports two drives that have different capacities, different
access times and different manufacturers without controller modification.
Drives with up to 16 heads and 4096 cylinders are supported by the
controller through the registers, 1024 cylinders via INT
13. Provides both
the highest capacity and highest performance.
Can support more than 1024 cylinders under DOS. A built-in partition
driver allows use of drives with more than 1024 cylinders under DOS.
Breaks the OOS INT 13 limit. See Appendix VIII for details.
Highest AT 2,7 RLL performance. The combination of non-interleaved
operation, low controller overhead, and 26 sectors per track give the ACB-
237X the highest transfer rate available today. This is from 700 Kilobytes
per second to as high as 750 Kilobytes per second data transfer depending
on system configuration, thus the highest system performance in
multitrack data transfers.
Non-interleaved operation. This gives the ability to read one track of data
in one disk revolution, the maximum rate that the drive can give data to the
controller. This provides the fastest controller/drive performance.
Most accurate 2,7RLL data separator. The AIC-6225 Data Separator chip
used in all Adaptec 2,7 RLL designs has the smallest data separator window
margin in the industry. For the ACB-237X, the window margin is 3.3
nanoseconds compared to 6-10 nanoseconds for the competition. This
insures the hightest data reliability for your valuable data.
Optional on-board Adaptec ACB-BIOS. This provides the most
functionality of any AT controller. The copyrighted ACB-BIOS contains
the low level format, defect management, data verification,
autoconfiguration of any drive without changing AT system BIOS, large
disk partitioning and OOS device driver. The ACB-BIOS functions are also
accessible by your customized redirected 1/0 drive configuration program.
ACB-237X
1 -2

Introduction
ACB-BIOS low-level primary format. This provides the ability
on
the
controller to format the drive without the need
of
system diagnostics
or
changing the AT system BIOS.
ACB-BIOS ability to
add
grown defects, save and protect all defect lists.
This gives the ability to run additional defect tests and add the defects to
those the manufacturer found. Also the controller saves and protects both
the manufacturer's and grown lists from accidental erasure, thus the highest
data reliability.
ACB-BIOS sector-level defect mapping. This flags a sector on the disk to
be unusable and reports to the operating system its location, giving system
level data integrity.
ACB-BIOS data verification using worst case data patterns. This tests the
disk with the worst possible combinations
of
data before valuable user data
is placed on the disk. This provides the highest data reliability.
ACB-BIOS autoconfiguration
of
any 2,7 RLL drive, not in
AT
system
BIOS. This allows any 2,7 RLL drive to
be
formatted and used without
changing
the
AT
system
BIOS
drive
tables.
This
simplifies
the
cumbersome task
of
changing EPROM drive tables to add 2,7 RLL. The
controller writes the drive parameters onto the drive during format and reads
them on power up. This is ideal for field upgrades since the controller does
not need to be hardware configured to the specific drive. This achieves the
highest drive flexibility possible.
ACB-BIOS large disk logical partitioning. Since many 2,7 RLL drives are
greater than the 32 MB limitation set
by
DOS 3.0, 3.1 and 3.2, this
allows you to divide the drive into volumes
of
any size up to 32
MB
each.
Up to 16 volumes can be defined on one drive
or
24 volumes on two
drives, maximizing the drive capacity under a DOS environment.
ACB-BIOS downloadable DOS driver. The ACB-BIOS has a device driver
that is downloaded to a floppy. This allows access to the 16
or
24 32 MB
volumes defined by the Large Disk Logical Partitioning. This gives all
of
1 - 3 adaptec

Section
One
the software necessary to go beyond 32 MB right on the controller, thus
reducing your support and eliminating the need to write a device driver.
XT
height board. This allows use in both XT and AT height machines,
thus giving you flexibility in choosing your machine's enclosure.
High component integration using Adaptec !Cs. Adaptec is committed to
IC developement in order to integrate and to reduce the price
of
both boards
and ICs. Adaptec's ICs are used in all Adaptec boards and in most integrated
drives on the market; therefore, Adaptec components are proven in
reliability and in high volume production.
Use
of
surface mount technology. Adaptec is committed to the leading edge
of
technology. Surface Mount Technology allows greater functionality in
smaller spaces, as well as higher reliability.
The
ACB-2372
has
these
additional
features:
Support
of
two
IBM
AT-type
floppy
disk
drives. Compatible with the
most popular IBM floppy capacities. This includes 360 KB and 1.2 MB
floppy capacities for 5 1/4" floppy compatibility. Also supports 3 1/2"
floppies that use the 5 1/4" floppy drive interface.
Analogfloppy data separator. This gives much higher data integrity than
digital data separators. Thus floppy data reliability and data retrievability are
improved over previous AT floppy controllers.
1.4
HARDWARE
AND
SOFTWARE
REQUIREMENTS
The
Adaptec ACB-2372 Hard Disk and Floppy Disk Controller has been
designed to run in IBM PC AT-compatible computers that do not have a separate
or embedded floppy disk controller.
The Adaptec ACB-2370 Hard Disk Controller has been designed to run in IBM
PC AT-compatible computers that have a separate or embedded floppy disk
controller.
ACB-237X
1-4

Introduction
In order to install an Adaptec ACB-237X into an IBM PC AT-compatible
computer, the following configuration is required:
1. ACB-2372: IBM PC AT-compatible computer without floppy disk
controller.
ACB-2370: IBM PC AT-compatible computer with floppy disk controller.
Note: Compatible computers are defined to have 110 bus speeds of 6 MHz with one 110
wait stale, 8 MHz with one 110 wait stale or JO MHz with two 110 wait states. 110 bus
speed is not the same as CPU or memory speeds. For example, a 16 MHz 286 or 386
machine typically runs the 110 bus aJ 8 MHz with one 110 wait state.
2. PC or MS-DOS Version 3.0 or higher. System and supplemental program
diskettes.
The ACB-237X will also run with non-DOS operating systems and
networks. Please refer to the appendix for operation with Interactive
System Unix V/386, SCO Xenix
V.2.x, Novell NetWare 2.x, OS/2 and
other operating systems.
3. A "set-up" diskette that allows the PC AT-compatible computer's
configuration RAM to
be set up (such as the diagnostics diskette IBM
supplies with its PC ATs.)
4. Adaptec ACB-2372 hard disk and floppy disk controller or ACB-2370 hard
disk controller.
5. A 2,7 RLL qualified Winchester disk drive (Ask your drive manufacturer if
your drive is qualified for 2,7 RLL data encoding).
6. 5 1/4"
or 3 1/2" floppy disk drive.
7. 20- and 34-pin flat
or twisted ribbon cables for hard disk.
8. 34-pin twisted ribbon cable for floppy disk.
1 -5 adaptec

Section Two
Hardware
Installation
2.1
INTRODUCTION
This section describes the steps necessary to install the ACB-237X board into
the computer. First, the operating environment, unpacking procedure and board
layout are described. This section also describes the integration
of
the drive and
controller into the computer.
2.2
ENVIRONMENTAL
REQUIREMENTS
The ACB-237X will perform properly over the following range
of
conditions:
Operating
Temperature:
Humidity (Noncondensing):
Altitude (Feet):
MTBF
(Hours):
2.3
UNPACKING
PROCEDURE
Storage
0° to 55°C (32° to 131°F)
-40° to 75°C (-8° to 167°F)
0% to 95%
10% to 95%
Sea level to 10,000
Sea level to 20,000
20,000
at
55°C
The
carrier is responsible for damage incurred during shipment. In
case
of
damage, have the carrier note the damage on both the delivery receipt and the
freight bill, then notify your freight company representative so that the necessary
insurance claims can
be
initiated.
2 - 1 adaptec

Section Two
After opening the shipping container, use the packing slip to verify receipt of
the individual items listed on the slip. Retain the shipping container and packing
material for possible later reuse should return
of the equipment to the factory or
distributor
be necessary.
CAUTION: THE ACB-237X LIKE ALL ELECTRONIC EQUIPMENT, IS
STATIC SENSITIVE. PLEASE TAKE THE PROPER PRECAUTIONS
WHEN HANDLING THE BOARD. KEEP THE BOARD IN ITS
CONDUCTIVE WRAPPING UNTIL IT IS READY TO BE CONFIGURED
AND INSTALLED IN YOUR SYSTEM.
2. 4 ACB-2372 BOARD LAYOUT
The ACB-2372 is shown in Figure 2-1. This figure shows the location of the
controller microcode, ACB-BIOS, jumpers and connectors. Note that Pin 1
of
the connectors is identified by a square solder pad on the solder side of the board.
The dimensions
of the board are:
Width:
Length:
Height
3.9 Inches
13.0 Inches
0.75 Inches
c:::J JS I. CON~ATA
Js[!l [!]J9 J1
J7 JS
J10
) AIC-6225 I
~ FDC765 D
c:::J
J16
AIC-270L
J11
D I
[AIC-610~
[AIC-~O~
DRIVE 1 DRIVE 0
CONTROL CABLE
J4 J3 J2
jJCODE
[AIC-2801
[]
J12
a::::::::I
D
~
~c::::I
J13
BIOS
J14 J15
E::E:J c::::J c::E:J c:::::J
J17 J18 J19 J20 J21 J22
••PIN 1 LOCATION
FIGURE 2-1. BOARD LAYOUT
ACB-237X
2-2

J11
0
Hardware
Installation
2.
S ACB-2370
BOARD
LAYOUT
The ACB-2370 is shown in Figure 2-2. This figure shows the location
of
the
controller microcode, ACB-BIOS, jumpers and connectors. Note that Pin 1
of
the connectors
is
identified
by
a square'solder pad on the solder side
of
the board.
The dimensions
of
the board are:
Width:
3.9
Inches
Length: 8.0 Inches
Height: 0.
75
Inches
ACB-2370
DRIVE1 DRIVE 0
CONTROL
CABLE
I
r:::J
~LJ
J12
~
~JO
-}MC-OD_E_!2-71-28-)
I
EJ EJ
B
G
~
BIOS 127128!
I
J10
&::=:J
• = PIN 1 LOCATION
FIGURE 2-2. BOARD LAYOUT
2-3
adaptec

Section Two
2.6
SYSTEM
REQUIREMENTS
The ACB-237X was designed
to
be
installed in an IBM PC AT-compatible
personal computer; thus, it requires the same system resources as the IBM
AT
hard disk controller.
TABLE 2-1. ACB-237X SYSTEM MEMORY MAP
110 Ports
Hard Disk -Primary
-Secondary
lFO,
lFl,
1F2,1F3,1F4,1F5,1F6,1F7,3F6,3F7
170,171,172,173,174,175,176,177,376,377
*Floppy Disk -Primary 3F0,3Fl,3F2,3F3,3F4,3F5
-Secondary 370,371,372,373,374,375
If
the BIOS is enabled:
BIOS Address -Primary
-Secondary
Temporary Drive
Parameters Table
*
ACB-2372 only
Drive
Power
16 Kbytes from C8000H through CBFFFH
16 Kbytes
CCOOOH
through CFFFFH
Interrupt locations 60H through 67H
The IBM PC AT internal power supply does have sufficient current to power
most hard disk drives in addition to its present load. Check with your drive
vendor for an accurate estimate
of
its specific powerrequirements.
ACB-237X
2-4

Hardware Installation
TABLE 2-2. ACB-2372 POWER REQUIREMENTS
(Typical)
+5V
Power------>
1.5 Amp
-5V
Power > Not
Used
+12V
Power >
130mA
-12V
Power >
50mA
TABLE 2-3. ACB-2370 POWER REQUIREMENTS
(Typical)
+5V
Power------>
1.5
Amp
-5V
Power > Not
Used
+12V
Power >
Not
Used
-12V
Power > Not
Used
CAUTION:
THE VALUES FOR THE
POWER
REQUIREMENTS
WERE
DETERMINED
BY
ACTUAL
MEASUREMENTS
IN
AN
IBM
PC
AT
WHILE THE CONTROLLER WAS
READING
A
HARD
DISK.
IF
THESE
VALUES
ARE
TO
BE
USED TO
DESIGN
THE CONTROLLER
INTO
A
SPECIFIC
APPLICATION,
AT
LEAST
20%
SHOULD
BE
ADDED
TO
THESE LISTED VALUES
AS
A
SAFETY
MARGIN.
2-5
adaptec

Section Two
2.
7
INTEGRATION
INTO
THE
SYSTEM
To install the Adaptec ACB-237X board into your system you must first
configure the drive(s), set the controller jumpers and connect the drive cables
properly. This section describes all
of
the necessary steps to successfully install
this hardware.
Step 1 Controller Jumper Setup and Definition
Check that the jumpers are set correctly for your application. Table 2-4 and 2-5
defines, in detail, connectors and jumper blocks.
TABLE 2-4. ACB-2372 CON1ROLLER JUMPER DEFINITIONS
Note: Jumper positions andpin numbers are definedfrom left to right, or top
to
bottom, where applicable per Figure 2-1.
An
asterisk(*) denotes jumpers that
are installed
for
a standard configuration
J1
Floppy Disk control and data cable (34-pin), Both drives
12 Hard disk control cable (34-pin), Both drives
J3
Hard disk data cable (20-pin), Firstdrive (Drive
1)
14
Hard disk data cable (20-pin), Second drive (Drive 2)
15
Drive activity LED -Pins
1,4
are
+5
Volts, Pins
2,3
are Signal
Ground
16
Manufacturing Test Points
J7
Manufacturing Test Points
J8 Manufacturing Test Points
J9 Manufacturing Test Points
JlO Manufacturing Test Points
J
11
Manufacturing Test Points
112 Adaptec ACB-BIOS address selection
*Position 1 and 2 Jumpered for BIOS address C8000 -CBFFF
Position 2 and 3 Jumpered for BIOS address
CCOOO-
CFFFF
No jumper ACB-BIOS disabled
Note: Install only one jumper on 112. No jumper should be installed
if
ACB-
BIOSDisabled.
ACB-237X
2-6

Hardware
Installation
TABLE
2-4. ACB-2372
CONTROLLER
JUMPER
DEFINITIONS (Continued)
Note: Jumper positions and
pin
numbers are defined from left
to
right,
or
top to
bottom, where applicable per Figure 2-1.
An
asterisk
(*)
denotes jumpers that are
installed
for
a standard configuration.
J13
J14
115
116
J17
J18
J19
120
J21
J22
Manufacturing
Test
Points
BOARD
CONFIGURATION
JUMPERS
Position 1 Hard DiskPort Addresses
Not
installed: primary address lFO -1F7
Installed: secondary address 170 -177
Position 2 Floppy
Disk
Port
Address
Not
installed: primary address
3FO
-
3F7
Installed: secondary address
370
-377
Position 3 Bus
Wait
State
Not
installed: Enabled
Installed: Disabled
Position 4 Drive Recal goes to track 0 minus 1
Not
installed: Enabled (ST238)
Installed: Disabled (ST4144R)
Position 5 NotUsed
Position
6
Serial Monitor
Mode
Not
installed: Disabled
Installed: Enabled (2400 baud)
Position 7 Manufacturing
Test
Point
Serial Monitor Output
Manufacturing
Test
Points
Not Used
NotUsed
Controller's system interrupt selection
*Pins 1 and 2
jumpered
for IRQ14
Pins 2 and 3 jumpered for IRQ15
Pins 3
and
4
DO
NOT
USE
Floppy Disk
DMA
Acknowledge signal selection
*Pins 1 and 2
jumpered
for
DACK2
Pins 2 and 3
jumpered
for DACK3
Floppy Disk InterruptRequest signal selection
Pins
1and2jumpered
for IRQIO
*Pins 2
and
3
jumpered
for
IRQ6
Floppy
Disk
DMA
Request signal selection
Pins 1 and 2
jumpered
for
DREQ3
*Pins 2 and 3 jumpered for
DREQ2
2-7
adaptec

Section
Two
TABLE 2-5. ACB-2370 CONTROLLER
WMPER
DEFINITIONS
Note: Jumper positions and
pin
numbers are defined from left to right, or top to
bottom, where applicable per Figure
2--2.
An
asterisk
(*)
denotes jumpers that are
installed
for
a standard configuration.
J1
Hard disk data cable (20-pin), second drive (Drive 2)
J2 Hard disk data cable (20-pin), first drive (Drive
1)
J3
Hard disk control cable (34-pin),
both
drives
J4 Manufacturing test points
JS
Drive activity LED -Pins 1,4 are
+5
Volts, Pins 2,3 are
signal ground
16
Board configurationjumpers
Position 1 Hard disk
port
addresses
Not installed: primary address
lFO
-
1F7
Installed: secondary address 170 -177
Position 2 Not
used
Position 3 Wait state (C
&
T)
Not installed: enabled
Installed: disabled
Position 4 Drive recal goes to track 0 minus 1
Not installed: enabled (ST238)
Installed: disabled (ST4144R)
Position 5 Not
used
Position 6 Serial monitor mode
Not installed: disabled
Installed: enabled (2400 baud)
Position 7 Manufacturing test point
J7 Manufacturing test points
J8 Manufacturing test points
19
Manufacturing test points
HO
Serial monitor output
J
11
Manufacturing test points
J12 Manufacturing test points
J13 Controller's system interrupt selection
*Pins
1and2
jumpered for IRQ14
Pins 2 and 3 jumpered for IRQ15
Pins 3 and 4 DO NOT USE
J14 Adaptec ACB-BIOS address selection
*Position 1 and 2 Jumpered for BIOS address C8000 -CBFFF
Position 2 and 3 Jumpered for BIOS address
CCOOO-
CFFFF
No jumper ACB-BIOS disabled
Note: Install only one jumper on 114. No jumper should be installed
if
ACB-BJOS is
disabled
J
15
Manufacturing test points
ACB-237X
2-8

Hardware
Installation
Step
2 Hard Disk Cabling, Drive Selection and Termination
The drive changeable parameters that must
be
set are the drive selection switches
(orjumpers) and the drive termination. The drive selection switches
and
cabling
select the address (drive address
1-4)
to which the drive will respond. This is
accomplished either
by
setting both drives to
be
the second lowest address and
using a twisted 34-pin cable,
or
by setting the drive address to the lowest two
addresses and using a flat cable.
A. Twisted 34-Pin Cable
The
typical AT 34-pin cable has three connectors. Between the first (middle)
drive connector (for drive D) and the second drive connector (for drive C), wires
25 through 29 are twisted, thus inverting the drive selection wires. This type
of
twisted
cable
allows both drives to have their drive selection switches (or
jumpers) to be the same. Both drives must be set to the SECOND lowest drive
address. The controller will
see
the two drives to
be
drive 1
and
drive 2,
depending on the position
of
the connector that is used.
B. Flat 34-Pin Cable
In some cases a 34-pin flat (non-twisted) cable is used. This cable does
not
invert the drive selection wires but relies on the drive addresses to
be
unique for
each drive. Now drive 1 must have its drive selection switches (or jumpers) set
to
be
the lowest drive address (typically 1). Drive 2 must have its selection
switches (orjumpers) set to
be
the second lowest drive address (typically 2). The
controller will see the two drives to be drive 1 and drive 2, independent
of
the
position on the connector that is used.
Before the drives can
be
cabled to the controller, the drive cable terminator must
be
properly set. The terminator is used to reduce signal "ringing" in the cables.
The terminator, as its name implies, must
be
at the
end
of
each cable in order to
have the controller
and
drive communicate properly.
The
controller has a
permanent terminator built into it. The disk drives, since they can
be
connected
in a daisy-chain configuration (see Figure 2-4), have a removable terminator.
This is usually a 16-pin DIP resistor package located on the drive PCB. The last
2-9
adaptec

Section
Two
physical drive in the chain must always have its terminator installed. When two
drives are connected to the same controller, only the last one in the daisy chain is
terminated (see Figures 2-3 and 2-4 for the ACB-2372. See Figures 2-5 and 2-6
for the ACB-2370). The other drive must have the terminator resistor removed.
Step 3 Floppy Disk Cabling, Drive Selection and Termination (ACB-2372
only)
The typical
AT
34-pin floppy disk cable has three connectors. Between the first
(middle) drive connector (for drive B) and the second drive connector (for drive A),
wires 10 through 16 are twisted, thus inverting the drive selection wires. This
type
of
twisted cable allows both drives to have their drive selection switches (or
jumpers) to be the same. Both drives must
be
set to the SECOND lowest drive
address (typically 1 since floppy drives are addressed as 0-3). The controller will
see the two drives to be drive 0 and drive
1,
depending on the position
of
the
connector that is used.
Termination
of
the floppy disk drives is the same as the hard disk drives in step
2.
ACB-237X
2-10