By Sven Pook
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.
Display of the 40 column feed is done through the composite signal. 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.
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.
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.
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.
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
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 €20,- excl. shipping from The Netherlands. For now orders can be placed by contacting me through one of the following options: