LSI 53C810A User Manual

Page 168

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6-28

Instruction Set of the I/O Processor

Jump Instruction
The LSI53C810A can do a true/false comparison of the
ALU carry bit, or compare the phase and/or data as
defined by the Phase Compare, Data Compare and
True/False bit fields.

If the comparisons are true, then it loads the

DMA

SCRIPTS Pointer (DSP)

register with the contents of the

DMA SCRIPTS Pointer Save (DSPS)

register. The

DMA

SCRIPTS Pointer (DSP)

register now contains the

address of the next instruction.

If the comparisons are false, the LSI53C810A fetches the
next instruction from the address pointed to by the

DMA

SCRIPTS Pointer (DSP)

register, leaving the instruction

pointer unchanged.

Call Instruction
The LSI53C810A can do a true/false comparison of the
ALU carry bit, or compare the phase and/or data as
defined by the Phase Compare, Data Compare, and
True/False bit fields.

If the comparisons are true, then it loads the

DMA

SCRIPTS Pointer (DSP)

register with the contents of the

DMA SCRIPTS Pointer Save (DSPS)

register and that

address value becomes the address of the next
instruction.

When the LSI53C810A executes a Call instruction, the
instruction pointer contained in the

DMA SCRIPTS

Pointer (DSP)

register is stored in the

Temporary (TEMP)

register. Since the TEMP register is not a stack and can
only hold one Dword, nested call instructions are not
allowed.

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

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