Computer Hardware User's Guide

No Operation
NOP
13-181
Assembly Language Instructions
Syntax NOP
src
Operation No ALU or multiplier operations.
AR
n
is modified if
src
is specified in indirect mode.
Operands
src
general addressing modes (G):
0 0 register(no operation)
1 0 indirect (modify AR
n
, 0
n
7)
(disp = 0–255, IR0, IR1)
Opcode
31 24 23 16 8 7 015
000 01 0
0 11
src
G 00 000
Description If the
src
operand is specified in the indirect mode, the specified addressing
operation is performed, and a dummy memory read occurs. If the
src
operand
is omitted, no operation is performed.
Cycles 1
Status Bits LUF Unaffected
LV Unaffected
UF Unaffected
N Unaffected
Z Unaffected
V Unaffected
C Unaffected
OVM Operation is not affected by OVM bit value.
Example 1 NOP
Before Instruction After Instruction
PC 3A PC 3B
Example 2 NOP *AR3––(1)
Before Instruction After Instruction
AR3 80 9900 AR3 80 98FF
PC 5 PC 6
Mode Bit