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Welcome to the Multi-EditorROM + 40/80 Column Switcher Page! This is a combination of two other projects with bits and pieces of other projects thrown in, to make an all-in-one PET/CBM "Personality Board". It has the following features:
NOTE: Composite and RGBI output require Editor ROM support for 15kHz refresh rate.
This board is the culmonation of several projects and ideas that I have had over the last several years. Commodore never sold a PET/CBM machine that could do both true 40 or 80 column video, which meant you couldn't have one machine that could run all PET/CBM software. There were "soft 40" solutions that turned an 80-column machine to 40 columns by re-programming the CRTC chip, but the 40-column mode was not "true" 40 columns like on a native 4032. It did this by increasing the left and right margins, effectivly making a squished 40-column display that did not fill the entire screen. There were 3rd-party solutions to do true 40/80 switching. One such solution was from the Comspec 40/80-S2, which I have cloned in another project. This is great, but switching modes requires a RESET in order to activate the proper Editor ROM. This board also mounts vertically with many flyout connections.
Commodore also did not have an Editor ROM that could handle both 40 and 80 columns at the same time, which is why the machine needs to reset. The Comspec board selected between one of two Editor ROMs depending on the selected video mode. I have a project that allows anyone to build their own Editor ROM by selecting which features they want. One of the things I did was integrate "soft 40" into it, but my goal all along was to have true 40/80 column switching via software. So, this board has the ability to toggle 40/80 via a special control line, such as one of the CRTC chip's upper addressing lines (which is currently unused).
Commodore PET/CBM's came in 40 or 80 column, and had two different keyboard layouts (or more if you count international versions). They came in 50 or 60 Hz power options, and they even had models with a power-on menuing system. My Editor ROM Project can add features like a built-in DOS Wedge, Keyboard reset, PAL or NTSC video support, and more. All of this means there are many Editor ROM combinations. This board contains my Multi-Editor ROM adapter functionality, which allows up to 16 different Editor ROMs, with each rom up to 4K in size. It is also possible to select between two ROMs the same as the Comspect 40/80 board using the toggle switch.
I wanted to reduce the flyouts. By incorporating the Editor ROM functionality it meant the board needed to mount flat on the jumper-block and the UD7 socket, thereby eliminating 3 flyouts.
Finally, I added composite video output, as well as an RGBI connection. These options require an Editor ROM that supports NTSC or PAL video refresh rates. These also may require that the video and sync signals be inverted, so there is an inverter on the board as well. This inverter is also handy for installing a motherboard in a case with 9" monitor.
This board was specifically designed for the 8032089 motherboard. You can identify this motherboard by looking for a block of jumpers near the ROM sockets. These jumpers are labelled BA0 to BA10 and the spacing between the jumpers is NOT even (there are 3 groups). The motherboard looks like this:
(click for bigger picture!)
The following 40xx and 80xx motherboards are NOT supported with the first revision:
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The 8032080 motherboard is VERY similar. It can be identified by the BA jumper block in the same location but with EQUAL spaced jumpers. This motherboard MAY work but there would have to be some modifications to the installation. You would need to raise up the board and use longer sockets so that the pins can be bent and installed onto the jumper locations. Also, the jumpers for the flyouts are in different locations.
The 8032030 motherboard does not have the BA jumpers at all. This motherboard ONLY DOES 80 COLUMN and is not compatible. Also, the motherboards in the 8296 or 8296-D are not compatible. If in doubt please contact me!
I have partially assembled and tested one board. The Multi-Edit and 40/80 switching capabilities are working as expected! Currently I have not populated the inverter or composite input sections. I installed the board in one of my 8032 machines and demonstrated it at the 2017 World of Commodore Show, Dec 9th and 10th in Toronto. It was a big hit!
I gave away some blank boards at the show, so I'll be working on putting together some build instructions.
Here is the Multi-EditROM + 40/80 Column Switcher schematic diagram and PCB:
The Kicad schematics and gerbers are available on Github here.
Here are assembly instructions for the board. This is currently a work in progress!
There are many Editor ROMs for the PET. Official ROMs from Commodore were made for different combinations of features:
Third-party Editor ROMs can also be used. My Editor Rom Project can build various "original" ROMs and also customized ROMs. For example:
MERB is a tool to help you assemble Editor ROM binaries for burning to EPROM.
MERB, with source code and executable, is available on Github
Here are some Editor ROM Sets. A "set" is a single 64KB file containing 16 Editor ROMs and should be burned to a 27512 EPROM.
| BINARY | CONTENTS | NOTES |
| MER-SET-02.bin | MER-SET-02.pdf | Recommended for PET with Business Keyboard. Soft40, SS40, Hardware 40/80 Switcher working. As installed and shown at WOC'2017. |
Page Created: Jul 21/2017. Last updated: Aug 2/2025, 8:00pm EST
Send comments or feedback to Steve Gray(sjgray@rogers.com)