Chapter
1.
Assembly
Language
and
Processors
Stack, I/O, and Machine Control Instructions. The following instructions affect the stack
and/or
stack pointer:
PUSH
POP
XTHL
SPHL
The
[/0
imtructiom
Me
dS
follows:
IN
OUT
Push
Twu
Bytes
of
Data
onto
the Stack
Pop
Two Bytes
of
Data off the Stack
Exch'lIlge Top
of
Stack with
Hand
L
Move
content'>
of
Hand
L to Stack Pointer
Initiate Input Operation
Initiate
Output
Operation
The machine contlo[
imtructiom
arc as follows:
EI
DI
HLT
NOP
Enab[e I
nterrupt System
Disable Interrupt System
Ha[t
No
Operdtion
HARDWARE/INSTRUCTION
SUMMARY
The following illustrations gl'aphic,!I[y summarize the instruction
'>et
by showing the hardware acted upon
by
,>pecific
in'>truction'>. The type
of
operanu al[owed for each instruction
is
inuicateu through the use
of
a code.
When no
(oue
i'>
given, the instruction uoes not a[low operands.
Code Meaning
REGM
S
The operand may specify one
of
the S-bit registers A,B,C,D,E,H, or L
or
M
(a
memo
-y
reference
via
the 16-bit address
in
the
Hand
L registers). The
MOV
instruction, which calls for two operands, can specify M for only one
of
it<,
operands.
Accumulator Instructions
Designates S-bit immediate operand.
Designates a 16-bit audress.
De,>ignates an
8-bit port number.
De,>ignatc'>
a 16-bit register pair (B&C,D&E,H&L, or SP).
Designate,> a
16-bit immediate operand.
The fo[lowing illustration shows the instructions that can affect the accumulator. The instructions listed above
the
accumu[dtor
a[1
act on the data
in
the accumulator, and
a[[
except
CMA
(complement accumulator) affect
one or
mmc
of
the conditioll
flag'>.
The instructions listed below the accumulator move data into or
out
of
the
accLlmu[dtor,
but
do not affect conditioll flags. The
STC
(set carry) and
CMC
(comp[ement carry) instructions
arc
also shown here.
ALL
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1·19
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