Hardware Configuration Requirements; Scsi Configuration - Adaptec AHA-1740A Technical Reference Manual

EISA-to-Fast SCSI Host Adapter

Hardware Configuration Requirements

The following host adapter configuration options must be defined prior to setting the
card enable bit in register zC84:
The BIOS location must be set to an address which does not conflict with
other system resources. It may also be enabled or disabled for the particular
board.
The interrupt channel needs to be selected and enabled. In addition, the inter-
rupt may be chosen to be high or low-level true.
The I/O port needs to be selected. The AHA-1740/1744 has two options, the
1540 interface or 1740 interface. If the 1540 interface is chosen, then the base
address must be set to the proper value. The default value should be 330h.
The AHA-1740/1744 can stay on the bus for a programmable amount of time
after preemption. The default value should be 2.
After these registers are programmed, the Card Enable bit, as defined in the
EISA specification, must be set. This indicates to the adapter that the regis-
ters are valid.

SCSI Configuration

To initialize the SCSI interface, first set the SCSI ID. Then the host adapter needs to
be told whether to issue a SCSI Reset on power-on. In order to facilitate power-up,
the BIOS needs information about the SCSI bus physical devices. It may be neces-
sary for the firmware to know this for future enhancements, so it is included in this
definition. This information is not key to operation, and is loaded separately by the
BIOS. Up to 16 devices are allowed for future expansion.
Send a SCSI Start command
Device supports more than one LUN
Enable/disable SCSI parity
Enable/disable synchronous negotiation
Maximum synchronous transfer rate
Enable/disable disconnection
Error condition if device not installed
Enable disk BIOS support
Include removable media in disk BIOS support
Hardware Functional Description
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