LSI LSI53C895A, Technical Manual

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5-26 SCSI SCRIPTS Instruction Set
5.6 Transfer Control Instructions
This section describes the Transfer Control Instructions. The
configuration of the OpCode bits define which Transfer Control Instruction
to perform.
5.6.1 First Dword
IT[1:0] Instruction Type - Transfer Control
Instruction
[31:30]
The IT bit configuration (10) defines the Transfer Control
Instruction Type.
OPC[2:0] OpCode [29:27]
This 3-bit field specifies the type of Transfer Control
Instruction to execute. All Transfer Control Instructions
can be conditional. They can be dependent on a
true/false comparison of the ALU Carry bit or a
comparison of the SCSI information transfer phase with
the Phase field, and/or a comparison of the First Byte
Received with the Data Compare field. Each instruction
can operate in Initiator or Target mode. Transfer Control
Instructions are shown in
Table 5.4 .
31 30 29 27 26 24 23 22 21 20 19 18 17 16 15 8 7 0
DMA Command (DCMD)
Register
DMA Byte Counter (DBC) Register
IT[1:0] OPC[2:0] SCSIP[2:0] RA R CT IF JMP CD CP WVP
DCM-Data Compare
Mask
DCV-Data Compare
Value
1 0 x x x x x x x 0 x x x x x x x x x x x x x x x x x x x x x x
Table 5.4 Transfer Control Instructions
OPC2 OPC1 OPC0 Instruction Defined
0 0 0 Jump
0 0 1 Call
0 1 0 Return
0 1 1 Interrupt
1 x x Reserved