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1
Getting Started
This guide provides the basic steps required for
®
installation of the AHA
-2740/2742 and the
AHA-2740-T/2742-T EISA-to-Fast SCSI Host
Adapters. Procedures for all adapters are the same
except when regarding the on-board floppy control-
ler on the AHA-2742/2742-T. Installation of the
host adapter includes:
1. Installing the AHA (Adaptec Host Adapter) board
in an EISA system.
2. Installing the SCSI cable(s) and SCSI peripheral
devices.
3. Terminating the SCSI bus.
4. Adjusting the host adapter configuration settings
if necessary.
5. Loading software if necessary.
2
Board Layout
Figure 1 shows the location of the major compo-
nents on the host adapter; Table 1 provides a
description of each component.
J1
U1
J2
U2
J4
J3
PIN 1
PIN 1
J5
U9
Figure 1. Host Adapter Board Layout
1
Table 1. Host Adapter Components
Location
J1
J2
J3
J4
J5
J6
U1
U2
U5
U9
U10
3
Default Settings
Your host adapter is already configured for the
majority of EISA class computers. Table 2 lists the
default settings of your host adapter. Refer to
Section
6
information on changing any of these settings:
Table 2. Host Adapter Default Settings
Description
Interrupt Level
Bus Release Time
U5
Data FIFO Threshold
Host Adapter BIOS Address
Host Adapter SCSI ID
SCSI Bus Parity
SCSI Selection Timeout
SCSI Bus Reset at Power-on
SCSI Bus Termination
Greater Than 1 GByte Support
More Than Two Drive Support
Removable Drive Support
The On-board Floppy Controller
(AHA-2742/2742-T only)
U10
J6
If your floppy diskette drives are already run-
ning under another controller, disable the
on-board floppy controller by removing the
jumper shunt on jumper J4.
Description
External LED Connector
Floppy Connector (AHA-2742/2742-T only)
SCSI Channel A Internal Connector
Floppy Enable Jumper
(AHA-2742/2742-T only)
SCSI Channel B Internal Connector
(AHA-2740-T/2742-T only)
SCSI Channel A External Connector
Floppy Controller (AHA-2742/2742-T only)
RAM
Host Adapter BIOS
AIC-7770 Bus Master SCSI Chip
AIC-701 Configuration Chip
, Configuring the Host Adapter for
Default Setting
IRQ 11
60 BCLKS
100%
D8000h
Device ID 7
Enabled
256 ms
Enabled
Enabled
Disabled
Disabled
Support removable
drive as boot device
only
2
To use the on-board floppy controller, leave the
jumper shunt installed on jumper J4 and then
disable your existing floppy controller; refer to
your computer or floppy controller user
documentation.
4
Installing the Host Adapter
Board Installation
CAUTION
Turn OFF and disconnect power to the system and
external equipment. Always refer to your system's
documentation for instructions on removing the
system cover and adding option boards.
1. Remove the cover of your EISA personal
computer to expose the EISA bus slots on the
motherboard.
2. Locate an unused EISA slot in your system which
supports bus master operations (refer to the
host system documentation for details) and
remove the corresponding slot cover.
3. Align and insert the host adapter in the EISA
slot. Secure the host adapter in your system.
5
Connecting Peripherals
Connecting Cables
SCSI devices are cabled together in a single
continuous daisy-chain of devices, called the
SCSI bus. SCSI Channel A and SCSI Channel B
(AHA-2740-T/2742-T only) can each accommodate
a SCSI bus with up to seven SCSI devices con-
nected. SCSI Channel A is comprised of both an
internal and external connector.
Note
Only Single-Ended SCSI devices are supported by the
AHA-2740/2742/2740-T/2742-T host adapters. Consult
your SCSI device user documentation.
Internal SCSI Cables
When connecting the 50-pin internal SCSI ribbon
cables to both the host adapter and internal SCSI
peripheral device(s), make sure that Pin 1
3
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