User guide

SC35 User Guide Ver 4.8 August 30, 2002 Page 4 of 25
3. GENERAL DESCRIPTION
3.1 SCSI Interface
An intelligent SCSI controller from NCR, the 53C90A, handles the SCSI
interface for the SC35. The 53C90A is SCSI-I and SCSI II compliant, and
automates much of the interface overhead. It has a 16 byte FIFO, a DMA
interface, and numerous command and control registers.
The SC35 employs the following attributes:
1. Single-ended drivers
2. Termination power derived from cable
3. Parity on the interface
4. "Hard" RESET implemented
5. No reservation queuing
The SC35 has implemented all mandatory SCSI-I and SCSI- II commands
and several optional commands to enhance functionality. The following is a
list of commands and their equivalent hexadecimal representation.
1. Test Unit Ready 00h M
2. Rezero Unit 01h O
3. Request Sense 03h M
4. Format Unit 04h M
5. Read 08h M
6. Write 0Ah O
7. Inquiry 12h M
8. Reserve Unit 16h M
9. Release Unit 17h M
10. Mode Sense 1Ah O
11. Send Diagnostics 1Dh M
12. Read Capacity 25h M
13. Extended Read 28h M
14. Extended Write 2Ah O
15. Erase 2Ch O
16. Verify 2Fh O
Notes: O = Optional M = Mandatory
The implemented messages on the SC35 are as follows:
1. Command Complete 00h Generated
2. Extended Message 01h Both
3. Init Detected Error 05h Received
4. Abort 06h Received
5. Message Reject 07h Generated
6. NoOp Message 08h Received
7. Message Parity Error 09h Received
8. Bus Device Reset 0Ch Received
9. Identify 80h Received