Read/Write Instructions; Move To/From Sfbr Cycles - LSI LSI53C875A Technical Manual

5.5.4 Move To/From SFBR Cycles

Table 5.3

Read/Write Instructions

OpCode 111
Operator Read-Modify-Write
000 Move data into register.
Syntax: "Move data8 to
RegA"
1
001 Shift register one bit to the
left and place the result in
the same register. Syntax:
"Move RegA SHL RegA"
010 OR data with register and
place the result in the same
register. Syntax: "Move
RegA | data8 to RegA"
011 XOR data with register and
place the result in the same
register. Syntax: "Move
RegA XOR data8 to RegA"
5-24
All operations are read-modify-writes. However, two registers are
involved, one of which is always the SFBR.
read-modify-write operations. The possible functions of this instruction
are:
Write one byte (value contained within the SCRIPTS instruction) into
any chip register.
Move to/from the 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 SFBR, the compare and jump, call, or
similar instructions are used to check the value.
A Move-to-SFBR followed by a Move-from-SFBR is used to perform
a register-to-register move.
OpCode 110
Move to SFBR
Move data into
Byte Received (SFBR)
register. Syntax: "Move
data8 to SFBR"
Shift register one bit to the
left and place the result in
the
Received (SFBR)
Syntax: "Move RegA SHL
SFBR"
OR data with register and
place the result in the
First Byte Received (SFBR)
register. Syntax: "Move
RegA | data8 to SFBR"
XOR data with register and
place the result in the
First Byte Received (SFBR)
register. Syntax: "Move
RegA XOR data8 to SFBR"
SCSI SCRIPTS Instruction Set
SCSI First
SCSI First Byte
register.
SCSI
SCSI
Table 5.3 shows the possible
OpCode 101
Move from SFBR
Move data into register.
Syntax: "Move data8 to
RegA"
Shift the SFBR register one
bit to the left and place the
result in the register. Syntax:
"Move SFBR SHL RegA"
OR data with SFBR and
place the result in the
register. Syntax: "Move
SFBR | data8 to RegA"
XOR data with SFBR and
place the result in the
register. Syntax: "Move
SFBR XOR data8 to RegA"