Pet 8296 missing board roms

[Blacklord]

Original post by pontium

Hi all!

I'm very surprised that I found a forum with commodore pet lovers.

I bought a no operating 8296(SK),because it's very difficult to find one.Well,as I saw the computer is really dead.
I started to restore it,and make it operational again.I found a destroyed power stabilizer(usual stuff) but also i found that 2 roms are missing from the board.It's "U9" and "U10" empty sockeds.

With a google search,I found some information and rom images from this chips.
I have willem programmer and I can burn new roms but what kind of roms I have to use to make them work with pet??Any idea??

Sorry for my bad english,I'm Greek...

Thank you for your time
Giorgos

[Blacklord]

Original post by pet1978

UE9 and UE10 are normally empty and are available for user or 3rd party roms. UE7 and UE8 should have ROMs. UE7 is a 16K ROM containing BASIC and Kernal routines (addresses $B000-$DFFF & $F000-$FFFF), UE8 is the 4K screen editor ($E000-$E7FF & $E900-$EFFF).

UE7 would take a 27128 16K EPROM
UE8 would take a 2532 4K EPROM
UE9 and UE10 would take 2516 2K EPROMS or 2532 4K EPROMS

See schematic: http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/8296/324644-1of9.gif

Info on 8296 ROMS: http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/8296/index.html

Dave

[Blacklord]

Original post by pontium

Thank you very very much for your fast reply with this useful information

I'm gonna buy a new stabillizer and test the system.

[Blacklord]

Original post by pontium

Restored power supply,but:
No "beep" sound on the begining,nothing on screen
Also PLA chip runs extremely hot,I think its broken.Ram seems to be ok with normal temp on all chips

I will follow the pla replacement with gal chip,but I have to built a programmer.Willem does not support gal programming

Thanks again for your help,
Giorgos

[Blacklord]

Original post by Nils Eilers

You don't need to buy a GAL programmer. If you can program 27C512 EPROMs with your Willem, you can do the PLA replacement with a 27C512 EPROM and an adapter. Take a look at http://www.vic20.de/html/eprom_pla_8296_und_c64.html - sorry, all german.

This fix works great, I used it to repair my CBM 8296-D.

If there are any questions, I'd like to help where I can.