Not to worry. It worked fine in an instrument for almost a month, before I replaced the PCB with the right tracks and removed this routine altogether.

MOV MIRHEX1, 0FFH is made alright in the second statement in the CHKLUP routine with a INC MIRHEX1.

And you are right when you say this is the largest and slowest code to do the job on hand. I never mentioned otherwise.

And the reason I never bothered about these two aspects when I wrote it, was that the PCB was made and instrument had to be delivered. Size and speed penalty had no relevance in THAT application.

Thanks for pointing out though.

Raghu