Scsi Phase Comparisons - LSI LSI53C875A Technical Manual

RA Relative Addressing Mode
When this bit is set, the 24-bit signed value in the
SCRIPTS Pointer Save (DSPS)
relative offset from the current DMA SCRIPTS Pointer
(DSP) address (which is pointing to the next instruction,
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.
Command
Jump/Call a Relative Address
Start execution at the current address plus (or minus) the
relative offset.
Command
Don't Care
The SCRIPTS program counter is a 32-bit value pointing
to the SCRIPTS currently under execution by the
LSI53C875A. The next address is formed by adding the
32-bit program counter to the 24-bit signed value of the
last 24 bits of the Jump or Call instruction. Because it is
Transfer Control Instructions
Table 5.5

SCSI Phase Comparisons

MSG C/D I/O
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Condition Codes
Absolute Alternate Address
Condition Codes
Alternate Jump Offset
SCSI Phase
Data-Out
Data-In
Command
Status
Reserved
Reserved
Message-Out
Message-In
DMA
register is used as a
23
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