am53c94 Advanced Micro Devices, am53c94 Datasheet - Page 24

• Manufacturer Part Number: am53c94
• Description: High Performance Scsi Controller
• Manufacturer: Advanced Micro Devices

24
Target Selected without ATN Steps
Target Select with ATN Steps, SCSI–2 Bit NOT SET
Target Select with ATN Steps, SCSI–2 Bit SET
Target Receive Command Steps
Target Disconnect Steps
Register (06H)
Register (06H)
Register (06H)
Register (06H)
Register (06H)
Internal State
Internal State
Internal State
Internal State
Internal State
Bits 2:0 (Hex)
Bits 2:0 (Hex)
Bits 2:0 (Hex)
Bits 2:0 (Hex)
Bits 2:0 (Hex)
AMD
2
1
2
1
0
2
1
0
2
1
0
5
4
0
6
5
402Parity error during second or third message byte
2
1
2
1
2
1
0
Interrupt Status
Interrupt Status
Interrupt Status
Interrupt Status
Interrupt Status
Register (05H)
Register (05H)
Register (05H)
Register (05H)
Register (05H)
Bits 7:0 (Hex)
Bits 7:0 (Hex)
Bits 7:0 (Hex)
Bits 7:0 (Hex)
Bits 7:0 (Hex)
11
11
01
01
01
12
12
12
02
02
02
12
12
02
02
02
18
18
08
08
28
18
18
Explanation
Selected; received entire CDB; check group code valid bit; initiator asserted ATN
in command phase
Sequence halted in command phase due to parity error; some CDB bytes may
not have been received; check FIFO flags; initiator asserted ATN in command
phase
Selected; received entire CDB; check group code valid bit
Sequence halted in command phase because of parity error; some CDB bytes
may not have been received; check FIFO flags
Selected; loaded bus ID into FIFO; null–byte message loaded into FIFO
Explanation
Selection complete; received one message byte and entire CDB; initiator as-
serted ATN during command phase
Halted in command phase; parity error and ATN true
Selected with ATN; stored bus ID and one message byte; sequence halted be-
cause ATN remained true after first message byte
Selection completed; received one message byte and the entire CDB
Sequence halted in command phase because of parity error; some CDB bytes
not received; check group code valid bit and FIFO flags
Selected with ATN; stored bus ID and one message byte; sequence halted be-
cause of parity error or invalid ID message
Explanation
Halted in command phase; parity error and ATN true
ATN remained true after third message byte
Selected with ATN; stored bus ID and one message byte; sequence halted be-
cause of parity error or invalid ID message
Selection completed; received three message bytes and the entire CDB
Received three message bytes then halted in command phase because of parity
error; some CDB bytes not received; check group code valid bit and FIFO flags
Explanation
Received entire CDB; initiator asserted ATN
Sequence halted during command transfer due to parity error; ATN asserted by
initiator
Received entire CDB
Sequence halted during command transfer due to parity error; check FIFO flags
Explanation
Disconnect steps fully executed; disconnected; bus is free
Two message bytes sent; sequence halted because initiator asserted ATN
One message byte sent; sequence halted because initiator asserted ATN
P R E L I M I N A R Y
Am53C94/Am53C96