Initialize Scsi Subsystem (Operation Code 10); Return Firmware Checksum (Operation Code 11); Write Adapter Channel 2 Buffer (Operation Code 1A) - Adaptec AHA-1740A Technical Reference Manual

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Byte Description
10 Disconnection Option
11-FF Reserved (00)
If the command completes normally, the HACC interrupt will be set to one. If the
mailbox area has not been properly initialized, all 17 bytes are still requested by the
host. If byte 4, the Number of Mailboxes, is zero, bytes 5-7 must be ignored.

Initialize SCSI Subsystem (Operation Code 10)

After receiving this command, the host adapter expects one byte from the host to con-
figure the SCSI bus.
Enable/Disable Disconnect/Reconnect
Enable/Disable Synchronous Negotiation
Enable/Disable SCSI Bus Parity

Return Firmware Checksum (Operation Code 11)

After receiving this command, the host adapter passes two bytes to the host which re-
flect the checksum of the Standard Mode micromode. Note that this checksum is not
marked on the board. The checksum on the EEPROM reflects an aggregate of the En-
hanced Mode, Standard Mode and download utility microcodes.

Write Adapter Channel 2 Buffer (Operation Code 1A)

After receiving this command, the host adapter expects three outbound information
bytes to be transferred which point to an area of 64 bytes in system RAM. The area
pointed to will be transferred to the host adapter's channel 2 buffer using the host
adapter's DMA circuitry. After completing the transfer of the 64 bytes from the indi-
cated buffer area to the host adapter, the HACC interrupt will be set indicating nor-
mal completion. This command is used in conjunction with the Read Channel 2
Buffer command for host adapter diagnostics. The channel 2 buffer is used for trans-
mission of all information except the actual data field between the host adapter and
the host system.
Byte 0
Byte 1
Byte 2
5-12
Buffer area address, Most significant byte
Buffer area address
Buffer area address, Least significant byte
AHA-1740A/1742A/1744
Meaning
Each bit corresponds to a SCSI
device, e.g., bit 0 corresponds to
the device at SCSI address 0.
When set to one, the host
adapter will prevent the SCSI
device from disconnecting.