P R E L I M I N A R Y
AMD
24
Am53C94/Am53C96
Target Selected without ATN Steps
Internal State
Interrupt Status
Register (06H)
Bits 2:0 (Hex)
2
Register (05H)
Bits 7:0 (Hex)
11
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
1
11
2
1
01
01
0
01
Target Select with ATN Steps, SCSI–2 Bit NOT SET
Internal State
Interrupt Status
Register (06H)
Register (05H)
Bits 2:0 (Hex)
Bits 7:0 (Hex)
2
12
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
1
0
12
12
2
1
02
02
0
02
Target Select with ATN Steps, SCSI–2 Bit SET
Internal State
Interrupt Status
Register (06H)
Register (05H)
Bits 2:0 (Hex)
Bits 7:0 (Hex)
5
4
0
Explanation
12
12
02
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
402Parity error during second or third message byte
6
5
02
02
Target Receive Command Steps
Internal State
Register (06H)
Bits 2:0 (Hex)
2
1
Interrupt Status
Register (05H)
Bits 7:0 (Hex)
18
18
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
2
1
08
08
Target Disconnect Steps
Internal State
Register (06H)
Bits 2:0 (Hex)
2
1
0
Interrupt Status
Register (05H)
Bits 7:0 (Hex)
28
18
18
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