iz8dwf | Commodore PET RAM/ROM replacement board, yet another one! @iz8dwf | Uploaded May 2018 | Updated October 2024, 55 minutes ago.
Here is my second revision of the CBM PET RAM/ROM replacement daughterboard. It's compatible with all PET revisions, it can map two complete ROM images (24Kbytes each) and has 2 additional 4K images that can be mapped in the kernel address range $F000 - $FFFF.
Each 4Kbytes ROM segment can be mapped separately either to the daughterboard 27512 EPROM or to the original mainboard ROM.
A board almost as small as possible, it doesn't use any programmable logic chip other than a 27(C)512 EPROM that can be programmed with almost any programmer out there.
An example of how I used this board to help troubleshooting a PET 2001 board can be seen here:
youtube.com/watch?v=Hgz1GqeprKE
Here is my second revision of the CBM PET RAM/ROM replacement daughterboard. It's compatible with all PET revisions, it can map two complete ROM images (24Kbytes each) and has 2 additional 4K images that can be mapped in the kernel address range $F000 - $FFFF.
Each 4Kbytes ROM segment can be mapped separately either to the daughterboard 27512 EPROM or to the original mainboard ROM.
A board almost as small as possible, it doesn't use any programmable logic chip other than a 27(C)512 EPROM that can be programmed with almost any programmer out there.
An example of how I used this board to help troubleshooting a PET 2001 board can be seen here:
youtube.com/watch?v=Hgz1GqeprKE
