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6 transfer control instructions, 1 first dword, Table 5.4 transfer control instructions – Avago Technologies LSI53C895A User Manual

Page 248: Transfer control instructions, First dword

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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