If you read my threads, I'm refering specifically to this link
http://www.aec_electronics.co.nz/

Probably because of the subject's title, whole disscussion de-railed badly. I found the solution, but for very strange reasons, every other things cloud the disscussion.

I will assembler the circuit, use the 89S53 for development(with ISP capability), 89C51/52 for final product (I have decades old, big and heavy, Hi-Lo ALL-07 programmer).

If you really follow MY THREADs, you'll enjoy "some kind of entertainment".

Sincere thanks to Jez Smith for the link.