3.
INSTRUCTION
SET
HOW
TO
USE
THIS
CHAPTER
This chapter
is
a dictionary of 8080 and 8085 instructions. The instruction descriptions are listed alphabetically
for quick reference. Each description
is
complete
so
that
you are seldom required to look elsewhere for addition-
al
information.
This reference format necessarily requires repetitive information.
If
you are readinr this manual to learn about
the
8080
or the 8085, do not try to read this chapter from
ACI
(add immediate with Carry) to XTHL (exchange
top
of
stack with
Hand
L registers). Instead, read the description of the processor and instruction set
in
Chapter 1 and the programming examples
in
Chapter 6. When you begin
to
have questions about particular
instructions, look them up
in
this chapter.
TIMING
INFORMATION
The instruction descriptions
in
this manual do not explicitly state execution timings. This
is
because the basic
operating speed of your processor depends on the clock frequency used
in
your system.
The
'state'
is
the basic unit
of
time measurement for the processor. A state may range from
480
nanoseconds
(320
nanosecond~
on the 8085) to 2 microseconds, depending on the clock frequency. When you know the
length
of
a state
in
your system, you can determine an instruction's basic execution time
by
multiplying that
figure
by
the number of states required for the instruction.
Notice that two sets
of
cycle/state specifications are given for 8085 conditional call and jump instructions. This
is
because the 8085 fetches the third instruction byte only
if
it
is
actually needed; i.e., the specified condition
is
sa
tisfied.
This basic timing factor
can
be
affected
by
the operating speed
of
the memory
in
your system. With a fast
clock cycle and a slow memory, the processor can outrun the memory.
In
this case, the processor must wait
for the memory
to
deliver the desired instruction or data.
In
applications with critical timing requirements, this
wait can be significant. Refer to the appropriate manufacturer's literature for memory timing data.
3-1
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