Avago Technologies LSI53C896 User Manual
Page 258
5-30
SCSI SCRIPTS Instruction Set
Version 3.3
Copyright © 1998–2003 by LSI Logic Corporation. All rights reserved.
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
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.
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 LSI53C896.
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 signed
(twos complement), the jump can be forward or backward.
MSG
C/D
I/O SCSI Phase
0
0
0
Data-Out
0
0
1
Data-In
0
1
0
Command
0
1
1
Status
1
0
0
Reserved-Out
1
0
1
Reserved-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