Hi Jeff,

See my comments

Jeff Corr wrote:
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$mod51

; IR Demodulator connected to P1.7 (Interupt 5)

MOV P2, #0000
If we assume this is the first line of your code, then this HAS to be JMP Start

JMP Start

ORG 0h

Hang on. Is this the start of your code ?
; Interupt 5 information

INT5: Where IS this interrupt vector ????

SetB P2.0 ; LED on P2.0 lights when INT5 triggered


RETI



ORG 100H ; Begin Program
Start:

MOV 0A8h, #10000001b
SETB EA
Make sure the int5 flag is CLEAR here before you enable it.
; Enable "Global" Interupts
MOV 0E8h, #11101000b ; Extended Interupt Enable (Should enable INT5)

Loop:

JMP LOOP ; Loop here waiting for INT5 to trigger


End