LSI LSI53C1000, Technical Manual

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5-30 SCSI SCRIPTS Instruction Set
SCSI bus. The following table describes the possible
combinations and their corresponding SCSI phase.
These bits are only valid when the LSI53C1000 is
operating in the initiator mode. Clear these bits when the
LSI53C1000 is operating in the target mode.
RA Relative Addressing Mode 23
When this bit is set, the 24-bit signed value in the DMA
SCRIPTS Pointer Save (DSPS) register is used as a
relative offset from the current DMA SCRIPTS Pointer
(DSP) address, which is pointing to the next instruction
and not the one currently executing. The relative mode
does not apply to Return and Interrupt SCRIPTS.
Jump/Call an Absolute Address
Start execution at the new absolute address.
Jump/Call a Relative Address
Start execution at the current address plus (or minus) the
relative offset.
The SCRIPTS program counter is a 32-bit value pointing
to the SCRIPTS currently under execution by the
LSI53C1000. The next address is formed by adding the
MSG C/D I/O SCSI Phase
0 0 0 ST Data-Out
0 0 1 ST Data-In
0 1 0 Command
0 1 1 Status
1 0 0 DT Data-Out
1 0 1 DT Data-In
1 1 0 Message-Out
1 1 1 Message-In
Command Condition Codes
Absolute Alternate Address
Command Condition Codes
Don’t Care Alternate Jump Offset