2-11
Host Adapter Configuration
AHA-1510A/20A Series User’s Guide
Stock Number: 510400-00, Rev. C Page: 2-11
Print Spec Number: 491842-00
Current Date: 11/18/94 ECN Date: 11/29/94
ISA Port Address
You probably will not need to change the port address, unless you
are installing more than one SCSI host adapter, or you kno w that the
current host adapter port address is in conflict with other devices.
Your host adapter must not share its ISA port address with any other
device on the computer. The default host adapter ISA port address is
340h. The alternate address is 140h. If you change the ISA port
address, refer to Chapter 4, Software Support, for info rmation on
modifying your ASPI Manager device driver.
SCSI BIOS
SCSI BIOS is enabled by default on the AHA-1520A/1522A host
adapters. This means the SCSI host adapter intercepts all hardware
interrupt 13 calls. If the SC SI BIOS is successfully inst alled, it can sup-
port up to two SCSI hard disks. Non-SC SI interrupt 13 calls are passed
to the motherboard BIOS.
SCSI Boot
SCSI boot capability is enabled by default (J5 pin pair BT jumper
on). This means the host adapter intercepts hardware inter rupt 19
during the boot process. If the SCSI boot process is successful, your
system boots from your SCSI hard disk set at SCSI ID 0. If not, hard-
ware interrupt 19 is passed either to another SCSI host adapter or to
the motherboard BIOS.
Caution: If you are using two AHA-1520A/1522A host
adapters, only one can have its SCSI boot enabled. If
both host adapters have SCSI boot enabled, your sys-
tem will hang.
ISA BIOS Address
You probably will not need to change the port address, unless you
are installing more than one SCSI host adapter, or you kno w that the
current host adapter BIOS address is causing a conflict in the system.
The default host adapter BIOS address is DC000. Three alternate
addresses are shown in Jumper Block J9 (AHA-1520A/1522A) on page
2-7. Each host adapter must have a unique ISA BIOS addres s. In
addition, SCSI BIOS must be enabled as described in Ju mper Block J5
on page 2-4.