This SCB command is used to send any SCSI command not supported by the adapter directly to a SCSI device. The command to be issued is placed at the end of the SCB. When commands are issued directly to a device using this command, messages are handled by the adapter. Data transfer direction is controlled by the read-option bit (RD) in the Enable word. When this bit is set to 1, the adapter transfers data to the system from the device. When the read-option bit is set to 0, the adapter transfers data to the device from the system. If the system-buffer byte count specified in the SCB is 0, no data is transferred. Because device data can be altered by this command, the cache is automatically cleared of any data from that device.

Note:

This command should be used only when other commands cannot perform the operation; otherwise, performance of the SCSI subsystem can be impacted.

This command should be issued only to logical device numbers 0 to 14.