PIC 16F628A won't program adres 0 correct?

[Tadango]

I have a home made programmer and it works perfect with all my PIC's except the 16F628A. Die 16F628 works ok. I tried 3 new PIC16F628A's and all won't program adres 0. After a bulk erase everythings reads 0x3FFFh. No mather what i program, adress 0 read's always 0. All other adresses verify ok. I use the exact same code and routines on all other pic's and they work fine. I checked the programming instructions many times but i cannot find enything wrong. Anyone got an idea?

[Tadango]

more test show that the first adres programmed results in 0. If i start in the middle of the chip is first writes a 0 and then the real data.

[Eric Brouwer]

The 16F628A uses a different programming sequence than the 16F628. Your programming software needs to be updated to also include support for the 16F628A.

[Tadango]

everyone says it is different but it's not. What is the difference? 0x08h is still the write command, if it's call erase program or program only does not matter. It is still the correct methode. All other writes are good, just not the first one :(

[Tadango]

mmh, is it possible that the 16F628A only accepts a NOP command (0x0000h) on adress 0? I read somewhere that is was nessesary for some debugger from microchip. Maybe this is the way to make sure the code is compattible ;)

I simple put a NOP command before my code and the chips works like it should... weird.