replace instruction. Figure 8-1 illustrates instructions
with their classification (read (R), store (S), or replace
(RP)).
l Read —Read instructions acquire an operand
from main memory.
l Store —Store instructions process an operand
already acquired and store it in main memory.
l Replace —Replace instructions acquire and
process an operand and then store it in memory.
INSTRUCTION LANGUAGE
INTERPRETATION
The instruction format provides the means to
customize each instruction. A list of instructions with
their formats, symbols, and meanings provides you a
means to interpret what an instruction will ultimately
accomplish. This is a very useful troubleshooting
tool to help isolate a specific malfunction. The in-
structions differ between types of computers. Take a
Figure 8-1.—Examples of computer instructions.
8-5
