Commodore 128 40/80 Column Video Adapter

By Sven Pook

A brief history

Ever since the Commodore 128 was launched in 1985 it had the ability to display information in 40 column mode or 80 column mode.

To do this, the computer had two video chips. The MOS VIC-II and the MOS VDC. To gain benefit from the 80 column VDC chip a monitor had to be used, but at that time these were fairly expensive. Therefore most people relied on the 40 column output. Nowadays most TV screens have the ability to display 80 column, but lack an appropriate connection for it to this vintage computer.

Various solutions have been made to attach a modern TV to the VDC chip of the Commodore 128, but were either rather expensive, looked amateuristic or could only display monochrome output.

That was up until now...

I was looking for a solution to be able to display 80 column video of my C128 onto my TV in color. Various schematics were out there, but all had different drawbacks. So I decided to encorporate them all into one design, thus creating the Commodore 128 40/80 Column Video Adapter.


  • Added a user manual, but I suspect the usage to be so straight forward that it is not needed. But feel free to download it via THIS link15-09-2021
  • After a dispute I have been banned from the Facebook Commodore 64/128 group. You can find me in various other C128 groups 10-09-2021
  • After and I am proud to announce that will be another supplier for the C128 40/80 Column Video Adapter 10-09-2021
  • There was a wrongful text on my website. The new adapters (V5 and V5.1) also have svideo/chroma-luma output in 40 column mode 10-09-2021
  • Added links to other youtube videos regarding this adapter 10-09-2021
  • The 3D printable housing is now available on Thingiverse 27-04-2021
  • @cheaplehre is working on redesigning the 3D printable housing to accomodate for the V5 adapter 13-04-2021
  • By demand I am proud to announce that V5 of the C128 40/80 Column Video Adapter is being distributed. This adapter supports S-Video (Chroma/Luma) in 40 column mode. A 3d printable case is being developed.11-04-2021
  • @cheaplehre has designed a bottom plate for the 3D printable housing to accomodate for the C128D (plastic case) 04-04-2021
  • New adapters boards are being designed. The first prototypes are on their way. 02-02-2021
  • Adapters are on their way to the US. These are sent in bulk to be redistributed once they arrive. This is done to reduce the cost of shipping, since shipping companies have drastically increased their rates due to Covid-19 18-01-2021
  • @cheaplehre has designed a 3D printable housing for the C128 40/80 Column Video Adapter. You can find it on thingiverse 15-01-2021
  • New adapters are being built on a regular basis, decreasing wait times to only a few days. Check Twitter and Facebook. 08-01-2021
  • As of 01-01-2021 due to Covid-19 transport companies have increased their rates. 08-01-2021
  • The C128 40/80 Column Video Adapter has had an upgrade. New cables have arrived. 08-01-2021
  • Due to quality issues with the short cable from the VIC-II chip to the adapter, production is delayed. 08-01-2021
  • News section has been added to keep you informed on what's going on. 08-01-2021

40 Column

40 Column VIC-II display

Display of the 40 column feed is done through either the composite (cvbs) or svideo/chroma-luma (y/c) signal. Eearlier adapters (V3 and V4) only had composite output for 40 column mode. The reason for this is that my particular TV did not have the ability to display RGBi and SVideo over the same connector, causing me to switch not only on the video adapter, but also on the TV. This is not what I wanted, so I decided the best option for me was to use the composite signal. Because a lot of people asked to encorporate the svideo signal too, I decided that all new models should have both capabilities.

80 Column

80 Column VDC display

The 80 column display consists of the VDC's RGB signals mixed with the intensity signal and a few resistors converting the signal from digital RGB to analogue RGB. To be able to display this in color a very low current has to be sent to the TV in order to "tell" it that it needs to switch from composite to RGB.

Audio output

Audio output on both displays

One other benefit of my adapter is that it provides audio output no matter what video signal you are using. The audio ouput is comming from the same connector which is being used for the 40 column display. But instead of interrupting this signal, it has a constant pass through.

The Commodore 128 40/80 Column Video Adapter in the media

Douglas Compton has done a very cool short review of the adapter in his 10 Minute Amiga Retro Cast. If you would like to see his review, please click this link to see it.
Other videos on youtube are:
10 Minute Amiga Retrocast - The Chickenhead Chronicles
Carpe Ludum
Patrick's Retro
Jerzy Jasonek

C128 40/80 Column Video Adapter V5 overview

C128 40/80 Column Video Adapter V5 composite/svideo switch

C128 40/80 Column Video Adapter V5 scart connector

3D printable housing for 40/80 Column Video Adapters V4 and V5 look like this

You can choose out of 4 different base plates, flat and for every type of C128

3D printable housing view at the scart connector

For people who do not have a scart connector on their TV, a scart to HDMI converter is a viable option. You can find these on Amazon, eBay or other tech websites

80 column display with 16 colors

40 column display

Ordering info

The C128 40/80 Column Adapter is not available in any store. Design of the PCB and manufacturing are done by myself.
The price for a C128 40/80 Columnd Video Adapter will be €22,- excl. shipping from The Netherlands. For now orders can be placed by contacting me through one of the following options or though one of my distributors:
note that the prices of these distributors may vary