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Recently I've become very interested in early PET/CBM boards and Commodore Prototypes. I like to study these boards and in some cases reverse-engineer them, and make modern replicas or enhanced boards.
The Commodore PET/CBM computers came standard with monochrome (green screen) text-only capabilities. Early PETs came only in 40 columns. There was no capability to change the built-in character set, or do bitmapped graphics. It wasn't long before add-on boards were available that could be installed inside the computers to enhance their capabilities. Graphics boards were released giving them true bitmapped graphics displays. These came in various forms from simple boards that expanded the existing capability, ones that added plain graphics, to boards that came with their own graphics processing chips. Eventually Commodore released 80-column machines, but until then boards were available to add 80-column capabiities to all the old 40 column machines. Not only that, but with Commodore you have to pick and choose between 40 or 80 columns. You couldn't have both. Luckily there were addon boards that could convert those 80-column machines to allow switching between 40 and 80 columns. There are add-ons that give you user-programmable fonts, and even to add colour to your PET!
Below you will find some pictures and info on some of the boards available. I gathered pictures from various places on the web, plus in some cases my own personal pictures in an attempt to provide a single reference point to show what was/is available and also to provide a quick summary and links to additional info where available.
If you know of any other boards, have a board you can donate, or just have additional info/pictures to share please contact Steve Gray.
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MTU K-1006 or 1007, Integrated Visible Memory Board For early PET/CBM. 320x200 pixels, light pen, rom expansion, KIM bus interface. MTU info can be found here. Released 1980. |
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Data Becker Graphics Board Plugs into CRTC socket and has a ribbon cable to the Character ROM. CRTC and Character ROM are transplanted to the board. Has a separate removable RAM board. Started with: sys36864 This board is being reverse engineered by Ruud Baltissen. Released 1981. |
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Dataview Graphics Board Mounts on expansion port of 4000/8000 series. Contains separate 6845 CRTC chip. Unknown release date. |
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Eltec petGRAFIK For 3016/3023. Mounts on older PET expansion port. Unknown release date. |
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Commodore High Speed Grafik A board containing a Thomson EF9365 or EF9366 Video Display Processor chip and 32K RAM. It plugs into the expansion port of 4000/8000 series or 8296 PETs. It has onboard firmware to support the card, plus a plug-in ROM with BASIC language extensions. The board does 512x256 or 512x512 pixel graphics depending on the installed chip. You can switch between the normal text screen or graphics either with a switch, or under software control. More info can be found here. Unknown release date. |
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Commodore HRE High Resolution Emulator Board. For 8296 only. Emulates the High Speed Graphik board. It installed on the CRTC and Character ROMs with a ribbon cable to the motherboard. There is a firmware ROM that plugs into the $9xxx socket. It does NOT have a Thomson VDP chip. It is called an "emulator" because the firmware is compatible with the HSG board while all drawing is done using software only. The board also does not contain any additional RAM as it uses the 8296's extra 64K RAM. Commodore released the 8296GD that apparently came standard with this board. Unknown release date. |
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HR8000 Plugs into 6502 socket. Uses a Thomson EF9366 Video Display Processor chip like the HSG board. Unknown release date. |
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HiRes Technologies Graphics Board Adds a separate 6845 CRTC chip. This board can create a bitmap up to 1024x512 pixels wide and display a window into that display on the normal text area. It gives you 700x200 or 640x200 visible pixels depending on the PET it is installed into. More info can be found here. Unknown release date. |
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SuperSoft HR40 and HR80 A board that plugs into the Editor ROM and Character ROM sockets with clip-on connection to the CRTC. Contains 8K RAM. There are two (or more) versions of this board. The HR40 works on 40-column machines, and the HR80 on 80-column. Both provide a resolution of 320x200 pixels. There is apparently also an HR80B version that contains 16K of RAM and produces 640x200 pixels on an 80-column PET. This board is being reverse-engineered. More info can be found here. Released 1982. |
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"MK" 80 column board Mounts on expansion port of 2001 series. Contains HD46505 CRTC chip. More pictures: 01, 02, 03, 04, 05 - Thanks to Matteucci Andrea! Released 1982. |
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"E.C.908" 80 column board Mounts on expansion port of 2001 series. Contains MC6845 CRTC chip. This appears to be an updated version of the "MK" board, differing in RAM. More pictures: 01, 02, 03. Unknown release date. |
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Delph Electronics 8000C For 3000/4000 series 40-column PETs. Adds 80-Column mode. Contains a separate 6845 CRTC chip and 2K or 4K RAM. Plugs into Editor ROM socket. This board is being reverse-engineered. More info can be found here. Unknown release date. |
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Comspec 40/80 S2 A small board for Universal Dynamic PETs that allows you to switch between 40 or 80 columns. This board has been reverse-engineered. More info can be found here and here. Unknown release date. |
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Multi-EditROM with 40/80 A small board for Universal Dynamic PETs that allows you to have multiple Editor ROMs plus the ability to switch between 40 or 80 columns either with a switch or via software control. This board includes the reverse-engineered Comspec 40/80 S2 circuit as well as a composite video out feature. More info can be found here. Hobby project, released 2017. |
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Execom 40/80 A small board that replaces the existing screen ram, plus a dual ROM board to hold both 40-column and 80-column ROMS. Unknown release date. |
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HAL PCG-6500 An external box that connects to the user port, with ribbon cable to the Character ROM. More info can be found here. Unknown release date. |
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ICT Programmable Character Generator A board designed to plug into a PET slot expansion system, with ribbon cable to the Character ROM. Contains 2K RAM for re-defining any/all standard PET 256 characters. Unknown release date. |
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Nils Eilers Programmable Character Generator A board with ribbon cable to the Character ROM. Contains 4K RAM for re-defining any/all standard PET 256 characters. More info can be found here. Hobby Project, released 2008. |
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EWW DOT Grafik A board that mounts on character rom socket, with ribbon cable to the expansion port. Includes option ROM. More pics: 02 , 03. Thanks to Ketsui for the pictures. Released 1981. |
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Microtech ColorChart A small board that plugs into any option ROM socket. Contains a 6847 Video Display Generator chip and 4K of RAM. It has a composite video output. Released 1982. |
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ColourPET-40/Dual Board A small board for Universal Dynamic PETs that gives 16 different forground and background colours for each character. It has a digital RGBI output for connection to standard CGA monitors. More info can be found here. Hobby project, released 2016. |
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Petunia by HUH Electronics Petunia is Composite video and 8-bit audio DAC board that plugs into the user and cassette ports. More info can be found here. Released 1978. |
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Unknown Composite Video with Audio Unknown Manufacturer. This board plugs into the User and Cassette ports. Video out is via an industrial connector and audio is via RCA jack. I purchased this from a TPUG member. Unknown release date. |
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D'Asaro Designs Composite Video Adapter for 2001 This is a small board that connects to the internal video port with a wire to +5V power. It provides composite video on an RCA jack. This board only works on early PET-2001 machines without CRTC controller. This board was based on a circuit from the Commodore PET Users Club of England. More info can be found here. Hobby Project. Unknown release date. |
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Internal Composite Video Adapter Home-made board that plugs in internally. Output is via RCA jack. This design also appears to be based on the circuit from the Commodore PET Users Club of England. Home-made circa 1980. |
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MTU K-1002-2 PET DAC Sound Board MTU K-1002-2 Hardware Music Board. 8-BIT DAC output. The board plugs into the User Port and Cassette Port. Output is via RCA jack. Original cost was $59, with an optional $20 software package. Released 1979. |
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Audio DAC by Michael Dunn R2R Resistor DAC board with onboard amplifier. Plugs into the User Port. More info can be found here. Unknown release date. |
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Homemade Audio DAC This is a Home-made Audio DAC that plugs into the User Port. It connects to an external amplifier. Made by myself from common plans. Homebrew, circa 1980. |
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PETSID board This is a Home-made expansion board that contains the famous SID chip, poviding 3 voices. More info can be found here. Homebrew, circa 2008. |
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Commodore High Speed Grafik This is the CBM-II version of the HSG board. It is an external box that plugs into the cartridge slot, however I have also seen this mounted internally in a CBM-II High Profile machine. More info can be found here. Unknown release date. |
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Unknown CBM-II B700 Hires Graphics Card A small board that plugs into the Character ROM and Video RAM, with connections to the user port. Contains 32K of RAM to provide a 640x350 pixel graphics screen. Thanks to Christian Forstrueter for pictures of the board. This board is being reverse-engineered. More info can be found here. Unknown release date. |
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HiRes Technologies Graphics Board HiRes Technologies advertised a board for the CBM-II, which sounded a lot like their PET board. We can assume it is based on the PET board but so far there are no known examples of the board in the wild. More info on the PET version can be found here. Unknown release date. |
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Commodore High Res Colour Graphic board This was in development at Commodore. It was based on the HSG board and the Thomson EF9365 VDP. Never released, but rumours say the board may have been in prototype stages. Never released. |
I'd like to thank the following people who have inspired and or contributed:
Date Created: Mar 9/2018. Last updated: Oct 22/2024, 4:00pm EST
Send comments or feedback to Steve Gray(sjgray@rogers.com)
