Intel mcs-48 manual Andport 4 Contents, With ACC Bits, MOV RO,#50 Move 50DEC to Address

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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