LSI LSI53C896, Technical Manual

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5-32 SCSI SCRIPTS Instruction Set
CD Compare Data 18
When this bit is set, the first byte received from the SCSI
data bus (contained in the
SCSI First Byte Received
(SFBR) register) is compared with the Data to be
Compared Field in the Transfer Control instruction. The
Wait for Valid Phase bit controls when this compare
occurs. The Jump if True/False bit determines the
condition (true or false) to branch on.
CP Compare Phase 17
When the LSI53C896 is in the initiator mode, this bit
controls phase compare operations. When this bit is set,
the SCSI phase signals (latched by SREQ/) are
compared to the Phase Field in the Transfer Control
instruction. If they match, the comparison is true. The
Wait for Valid Phase bit controls when the compare
occurs. When the LSI53C896 is operating in the target
mode and this bit is set it tests for an active SCSI SATN/
signal.
VP Wait For Valid Phase 16
If the Wait for Valid Phase bit is set, the LSI53C896 waits
for a previously unserviced phase before comparing the
SCSI phase and data.
If the Wait for Valid Phase bit is cleared, the LSI53C896
compares the SCSI phase and data immediately.
MC Data Compare Mask [15:8]
The Data Compare Mask allows a SCRIPTS to test
certain bits within a data byte. During the data compare,
if any mask bits are set, the corresponding bit in the
SCSI
First Byte Received (SFBR) data byte is ignored. For
instance, a mask of 0b01111111 and data compare value
of 0b1XXXXXXX allows the SCRIPTS processor to
determine whether or not the high-order bit is set while
ignoring the remaining bits.
Bit 19
Result of
Compare
Action
0 False Jump Taken
0 True No Jump
1 False No Jump
1 True Jump Taken
*