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This is the third part of the restoration of a Commodore Pet 'Fat 40' 4032. You might want to start at Part 1. The story so far: empty 4032 case being filled with parts from a donor rusty 8032-SK. The main board cleaned up quite well, there were a number of chips corroded, which needed replacing. Three of the 40 pin chips and three of the 24 pin ROMs were socketed, and the sockets all looked a bit suspicious. In the end, I removed and socketed all the 40 pin chips and the 24 pin ROMs.
- A 6520 PIA for the GPIB/IEE488 interface
- A 6522 VIA for the user port and cassette interfaces
- A 6502 CPU
- A 6545 CRTC display controller
- A 6520 PIA for the keyboard
6502 ROM/RAM replacement boards, the Pet was the main reason for I built those. It is a great tool to have at this point, as it can bypass the onboard ROM, RAM and glue logic and at least get the CPU up and running. Credit again to the original designer of the ROM/RAM board. His site has GAL logic terms for 2001 Pets, VIC20's and disk drives. So I had to write the terms for the 8032. It turned out not to be too different to the 2001, just a larger ROM area for the BASIC 4, and I changed the RAM options to 16K or 32K.
zimmers.net. The 4032 and the 8032-SK would have had almost the same set of ROMS:
- 901465-22 - 4K BASIC 4 Kernal
- 901474-04 - 2K Editor
- 901465-21 - 4K BASIC 4 ROM
- 901465-20 - 4K BASIC 4 ROM
- 901465-23 - 4K BASIC 4 ROM
Vintage Computer Forum has merged those to create the missing 80 N. That is what I have used for the moment, as the board is 80 column, but the keyboard is Normal.. Since there is space for 4 sets of ROMs, I had one with 80 N 50, one 80 B 50 and one 40 N 50. I also added an 80 column memory test ROM image (I'll insert the link when I find it).
fix the video circuits.....
The new V2.0 6502 ROM/RAM boards are available now.
The V3.1 ROM/RAM boards are now available.
2022 Update: A redesigned small version of the PET ROM/RAM boards are still available from TFW8b.com