Hi everyone. I have resolved the root cause of my 3 previous posts. If I can save just one person from the programming grief I had it will be worthwhile.

Suncoast Technologies of Florida,USA sells an 8051 & 2864 EEPROM based circuit board kit #70691HEX, based on an old DOS program and a bootloader EPROM. It has been sold often on eBay.

Fault: the bootloader removes code spacing when loading the EEPROM, meaning that all data tables and C functions and ASM subroutines (as well as .ORG directives in A51) not immediately following the main routine are rendered useless. This will cause program crashes in many instances, and is not documented.

This means that you can sadly forget about using a C compiler like Keil, for example.

I emailed the person in charge before posting on 8052.com; the issue was not resolved satisfactorily.
His unrelated post is here:http://www.8052.com/forum/rea...253

Thanks to everyone's advice in the forum. I spent DAYS reprogramming, disassembling, and testing programs in ASM and C 'til I traced down the problem in the EEPROM image of the bootloader.

I will be happy to provide documented proof of the fault if disputed.

Successfully using an EPROM programmer instead,
Marty :)