
5-24
Instruction Set of the I/O Processor
When the SYM53C710 executes a Call instruction, the
instruction pointer contained in the
DMA SCRIPTS
Pointer (DSP)
register is stored in the
Temporary Stack
(TEMP)
register.
When a Return instruction is executed, the value stored
in the
Temporary Stack (TEMP)
register is returned to the
DMA SCRIPTS Pointer (DSP)
register.
If the comparisons are false, the SYM53C710 fetches the
next instruction from the address pointed to by the
DMA
SCRIPTS Pointer (DSP)
register and the instruction
pointer is not modified.
Note:
The Memory Move instruction destroys the return address
stored in the
Temporary Stack (TEMP)
register.
Return Instruction
The SYM53C710 compares the phase and/or data as
defined by the Phase Compare, Data Compare, and
True/False bit fields. If the comparisons are true, then the
SYM53C710 loads the
DMA SCRIPTS Pointer (DSP)
register with the contents of the
Temporary Stack (TEMP)
register. That address value becomes the address of the
next instruction.
When the SYM53C710 executes a Call instruction, the
current instruction pointer contained in the
DMA
SCRIPTS Pointer (DSP)
register is stored in the
Tempo-
rary Stack (TEMP)
register.
When a Return instruction is executed, the value stored
in the
Temporary Stack (TEMP)
register is returned to the
DMA SCRIPTS Pointer (DSP)
register.
The SYM53C710 does not check to see whether the Call
instruction has already been executed. It does not
generate an interrupt if a Return instruction is executed
without previously executing a Call instruction.
If the comparisons are false, then the SYM53C710
fetches the next instruction from the address pointed to
by the
DMA SCRIPTS Pointer (DSP)
register and the
instruction pointer is not modified.
Note:
The Memory Move instruction destroys the return address
stored in the
Temporary Stack (TEMP)
register.