Ijaz:
1) Any programmable device has a specific programming algorithm, and if programmed according to the algorithm, it must retain the program forever.
That is correct

Ijaz:
2) What difference is there between a home made programmer and professional programmer, that in former case data retention time is <1 year and in later case the data retention time is forever.
That with a professional programmer the adherence to the parametres is verified, with a home made programmer often the product is "tested ok"

Ijaz:
3) If I believe that you are right in your claim, then it is apparent that programming algorithm specified in the data sheet is wrong, and the correct programming algorithm is only supplied/available to device progranmmer manufacturers like BP, Hi-Lo system, ADVIN etc.
I know of no such.

For instance, there are "programmers" out there that work very well if the clock speed of the PC you are using is the same as the "developers". I have no doubt that there are very good home made programmers, just that the verification of voltages and pulse widths often is lacking. Also, some have a lack of portability.

BP, for instance, would be hit with a major lawsuit if the chips did not hold. The creator of a "free" home made design would say "sorry, that is a glitch".

I have no adversity against home-made programmers, just if you are programming chips for production, use a professional or VERIFY ALL PULSES AND VOLTAGES from your home-made, who knows if the "developer" has done so.

Peter
Maybe this discussion can help to make also Windows software developers sensitive for comfort in respect of daily usage.
That will happen the day that pigs grow wings.


Erik