Avago Technologies LSI53C876E - Manual (Page 218)

5-28 SCSI SCRIPTS Instruction Set
Call Instruction
The LSI53C876 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, 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 LSI53C876 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.
If the comparisons are false, the LSI53C876 fetches the
next instruction from the address pointed to by the
DMA
SCRIPTS Pointer (DSP) register and the instruction
pointer is not modified.