LSI 53C875A Manuel D’Utilisation
5-20
SCSI SCRIPTS Instruction Set
Table Relative
Treats the alternate jump address as a relative jump and
fetches the device ID, synchronous offset, and
synchronous period indirectly. The value in bits [23:0] of
the first four bytes of the SCRIPTS instruction is added
to the data structure base address to form the fetch
address.
fetches the device ID, synchronous offset, and
synchronous period indirectly. The value in bits [23:0] of
the first four bytes of the SCRIPTS instruction is added
to the data structure base address to form the fetch
address.
Sel
Select with ATN/
24
This bit specifies whether SATN/ is asserted during the
selection phase when the LSI53C875A is executing a
Select instruction. When operating in Initiator mode, set
this bit for the Select instruction. If this bit is set on any
other I/O instruction, an illegal instruction interrupt is
generated.
selection phase when the LSI53C875A is executing a
Select instruction. When operating in Initiator mode, set
this bit for the Select instruction. If this bit is set on any
other I/O instruction, an illegal instruction interrupt is
generated.
R
Reserved
[23:20]
ENDID[3:0]
Encoded SCSI Destination ID
[19:16]
This 4-bit field specifies the destination SCSI ID for an I/O
instruction.
instruction.
R
Reserved
[15:11]
CC
Set/Clear Carry
10
This bit is used in conjunction with a Set or Clear
instruction to set or clear the Carry bit. Setting this bit
with a Set instruction asserts the Carry bit in the ALU.
Clearing this bit with a Clear instruction deasserts the
Carry bit in the ALU.
instruction to set or clear the Carry bit. Setting this bit
with a Set instruction asserts the Carry bit in the ALU.
Clearing this bit with a Clear instruction deasserts the
Carry bit in the ALU.
TM
Set/Clear Target Mode
9
This bit is used in conjunction with a Set or Clear
instruction to set or clear Target mode. Setting this bit
with a Set instruction configures the LSI53C875A as a
Target device (this sets bit 0 of the
instruction to set or clear Target mode. Setting this bit
with a Set instruction configures the LSI53C875A as a
Target device (this sets bit 0 of the
register). Clearing this bit with a Clear
instruction configures the LSI53C875A as an Initiator
device (this clears bit 0 of the SCNTL0 register).
device (this clears bit 0 of the SCNTL0 register).
Command
Table Offset
Absolute Jump Offset