6.5 Read/Write Instructions

The Read/Write instruction type moves the contents of one register to another, or performs arithmetic operations such as AND, OR, XOR, Addition, and Shift.

6.5.1 First Dword

 

 

IT[1:0]

Instruction Type - Read/Write Instruction

[31:30]

 

The Read/Write instruction uses operator bits 26 through

 

24 in conjunction with the opcode bits to determine which

 

instruction is currently selected.

 

OPC[2:0]

OpCode

[29:27]

 

The combinations of these bits determine if the

 

 

instruction is a Read/Write or an I/O instruction. Opcodes

 

0b000 through 0b100 are considered I/O instructions.

 

Refer to Table 6.2 for field definitions.

 

O[2:0]

Operator

[26:24]

 

These bits are used in conjunction with the opcode bits

 

to determine which instruction is currently selected. Refer

 

to Table 6.2 for field definitions.

 

A[6:0]

Register Address - A[6:0]

[22:16]

 

It is possible to change register values from SCRIPTS in

 

read-modify-write cycles or move to/from SFBR cycles.

 

A[6:0] select an 8-bit source/destination register within

 

the LSI53C810A.

 

6.5.2 Second Dword

Destination Address

[31:0]

This field contains the 32-bit destination address where the data is to move.

6.5.3 Read-Modify-Write Cycles

During these cycles the register is read, the selected operation is performed, and the result is written back to the source register.

Read/Write Instructions

6-23

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LSI 53C810A technical manual Read/Write Instructions, Read-Modify-Write Cycles