Avago Technologies LSI53C1000R - Manual (Page 267)

Read/Write Instructions 5-25
Version 2.2 Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
(subtrahend) with 0xFF, and add 1 to the resulting value. This creates the
twos complement of the subtrahend. The two values are then added to
obtain the difference.
5.4.4 Move to/from SFBR Cycles
All operations are read-modify-writes. However, two registers are
involved, one of which is always the
SCSI First Byte Received (SFBR) .
The possible functions of this instruction are:
•
Write one byte (value contained within the SCRIPTS instruction) into
any chip register.
•
Move to/from the SCSI First Byte Received (SFBR) from/to any other
register.
•
Alter the value of a register with AND, OR, ADD, XOR, SHIFT LEFT,
or SHIFT RIGHT operators.
•
After moving values to the SCSI First Byte Received (SFBR) , the
compare and jump, call, or similar instructions check the value.
•
A Move-to-SFBR followed by a Move-from-SFBR performs a register
to register move.
Table 5.1 Read/Write Instructions
1
Operator
Opcode 111
Read Modify Write Opcode 110
Move to SFBR Opcode 101
Move from SFBR
000 Move data into register.
Syntax: “Move data8 to
RegA” Move data into SCSI First
Byte Received (SFBR)
register. Syntax: “Move
data8 to SFBR”
Move data into register.
Syntax: “Move data8 to
RegA”
001
2
Shift register one bit to the
left and place the result in
the same register. Syntax:
“Move RegA SHL RegA” Shift register one bit to the
left and place the result in
the
SCSI First Byte
Received (SFBR) register.
Syntax: “Move RegA SHL
SFBR”
Shift the SFBR register one
bit to the left and place the
result in the register. Syntax:
“Move SFBR SHL RegA”
010 OR data with register and
place the result in the same
register. Syntax: “Move
RegA | data8 to RegA” OR data with register and
place the result in the
SCSI
First Byte Received (SFBR)
register. Syntax: “Move
RegA | data8 to SFBR”
OR data with SFBR and
place the result in the
register. Syntax: “Move
SFBR | data8 to RegA”