Return Installed Devices (Operation Code 0A) - Adaptec AHA-1740A Technical Reference Manual

EISA-to-Fast SCSI Host Adapter
Data Byte 0
80-FFh
Due to the internal differences between the AHA-1740A/1742A/1744 and earlier host
adapters, the data is not actually used but is saved and returned in the Return Setup
Data command. The command is accepted only for compatibility.
After completing this command, HACC is set indicating normal completion.

Return Installed Devices (Operation Code 0A)

This command returns information about which SCSI Targets and Logical Units
(LUs) are installed on the SCSI bus. The host adapter issues the SCSI Test Unit
Ready command to each target/LUN combination and reports the results using eight
bytes of data returned through the Data In register. A bit having a value of one indi-
cates that the associated LU is installed. Each byte is associated with the correspond-
ing target. Each bit within a target byte is associated with a particular Logical Unit,
bit 7 indicating the presence of LU 7 and so forth. The state of the target is analyzed
using the SCSI Test UnitReady command, analyzing the returned data to determine
if the addressed LU is available.
AT Bus Transfer Speed
Bit
7 1
6-4 000
001
010
011
100
101
110
111
3 0
1
2-0 000
001
010
011
100
101
110
111
Standard Mode Firmware Description
Custom Transfer Speed
Read Pulse Width (ns) = 100
Read Pulse Width (ns) = 150
Read Pulse Width (ns) = 200
Read Pulse Width (ns) = 250
Read Pulse Width (ns) = 300
Read Pulse Width (ns) = 350
Read Pulse Width (ns) = 400
Read Pulse Width (ns) = 450
Strobe off time = 100ns
Strobe off time = 150ns
Write Pulse Width (ns) = 100
Write Pulse Width (ns) = 150
Write Pulse Width (ns) = 200
Write Pulse Width (ns) = 250
Write Pulse Width (ns) = 300
Write Pulse Width (ns) = 350
Write Pulse Width (ns) = 400
Write Pulse Width (ns) = 450
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