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
