Note That - Intel MCS48 User Manual

INSTRUCTION SET
RETR
Return With
PSW
Restore (Not
in
8021
,
8022)
100
1
00
11
This
is
a 2-cycle
instruction.
The
stack pointer
is
decremented.
The program
counter
and
bits
4-7
of
the
PSW
are
then restored
from
the
stack.
Note
that
RETR
should be used to return
from an
interrupt,
but
should not
be used
within the interrupt service
routine as
it
signals the
end
of
an
interrupt routine
by
resetting the Interrupt
in
Progress
flipflop.
(SP)--
(SP)-1
(PC)--
((SP))
(PSW
4-7)-*- ((SP))
RL
A
Rotate
Left
Without Carry
1110
111
The
contents
of
the
accumulator
are rotated
left
one
bit.
Bit
7
is
rotated into
the
bit
position.
(An+1)-«-
(An)
(A0)—
(A7)
n=0-6
Example:
Assume
accumulator
contains 10110001.
RLNC: RL
A
;NEW
ACC CONTENTS ARE
01100011.
RLC A
Rotate
Left
Through Carry
Example:
1111
111
The
contents
of the
accumulator are rotated
left
one
bit.
Bit
7
replaces the carry
bit;
the carry
bit
is
rotated into
the
bit
position.
n=0-6
(An+1)-*- (An)
(A0)—
(C)
(O—
(A7)
Assume
accumulator
contains
a 'signed'
number;
isolate
sign
without
changing
value.
RLTC:
CLR C
RLC
A
RR A
CLEAR CARRY TO ZERO
ROTATE
ACC
LEFT,
SIGN
BIT
(7)
IS
PLACED
IN
CARRY
ROTATE ACC
RIGHT
—
VALUE
(BITS
0-6) IS
RESTORED,
;CARRY
UNCHANGED,
BIT
7
;IS
ZERO
Mnemonics
copyright
Intel
Corporation 1976.
4-30