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INSTRUCTION SET
Note: The mapping
of
port 'p' to opcode bits
0-1
is
as
follows:
1 0 Port
o 0 4
015
1 0 6
1 1 7
Example: ANDP4: ANLD P4,A ;'AND' PORT 4 CONTENTS
;WITH ACC BITS 0-3
CALL
address
Subroutine Call
la10a9as1101001
la7asa5a41a3a2a1aol
This is a 2-cycle instruction. The program counter and
PSW bits 4-7 are saved in the stack. The stack pOinter
(pSW
bits 0-2) is updated. Program control is then
passed
to
the location specified by 'address'.
PC
bit
11
is determined by the most recent SEL MB instruction.
A
CALL
cannot begin in locations 2046-2047
or
4094-4095.
Execution continues at the instruction following the
CALL
upon return from the subroutine.
((SP))
....
(PC), (PSW 4-7)
(SP)
....
(SP)+1
(PCS-10)
....
(addrS-10)
(PCO-7)
....
addrO-7
(PC
11
)
....
DBF
Example: Add three groups of two numbers. Put subtotals in
locations
50,
51
and total in location
52.
MOV
RO,#50
;MOVE '50' DEC
TO
ADDRESS
;REG 0
BEGADD: MOV
A,R1
;MOVE CONTENTS
OF
REG 1
;TO ACC
ADD A,R2 ;ADD
REG
2 TO ACC
CALL
SUBTOT;CALL
SUBROUTINE 'SUBTOT'
ADD A
R3
;ADD
REG
3 TO ACC
ADD A,R4 ;ADD REG 4 TO ACC
CALL
SUBTOT ;CALL SUBROUTINE 'SUBTOT'
ADD A,R5 ;ADD
REG
5 TO ACC
ADD A,R6 ;ADD
REG
6 TO ACC
CALL SUBTOT ;CALL SUBROUTINE 'SUBTOT'
SUBTOT: MOV
@RO,A
;MOVE CONTENTS
OF
ACC TO
;LOCATION ADDRESSED
BY
;REG
0
INC
RO
;INCREMENT
REG
0
RET ;RETURN TO MAIN PROGRAM
Mnemonics copyright Intel Corporation
1976.
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