EchoSIOInt.asm

Language: 8080 Assembly
Last Modified: 2022-11-14 1:09:26 AM UTC
File Size: 933 bytes

http://www.penguinstew.ca/example/AltairSerialEcho/EchoSIOInt.asm

; Echo SIO with interupts

ORG 0000H

LXI SP, 0100H ; 0000: 31 00 01 Initalize stack pointer

MVI A, 01H ; 0003: 3E 01

OUT 00H ; 0005: D3 00 Enable SIO input interupt

EI ; 0007: FB Enable CPU interupts

LOOP: NOP ; 0008: 00

NOP ; 0009: 00

NOP ; 000A: 00

JMP LOOP ; 000B: C3 08 00 Program loop

ORG 0038H ; Interupt Handler

PUSH A ; 0038: F5 Save value of accumulator and PSW

IN 01H ; 0039: DB 01

OUT 01H ; 003B: D3 01 Echo value

POP A ; 003D: F1 Restore accumulator and PSW

EI ; 003E: FB Renable interupts

RET ; 003F: C9 return