How to make PCBs
18 July 2022
Commodore 16 RAM expansion
5 August 2022
Diagnostics for the VIC20
A bit like the diagnostic card used in the Commodore 64, this card, complete with its cables to be inserted on the VIC20 ports, is capable of diagnosing problems with RAM or ROMs and other integrated devices. The substantial difference compared to the 64 deadtest is that it is not able to exclude the Kernal, this must be functional in order to direct the processor to read from the cartridge otherwise we will have a black screen.
I used a SuperExpander II as a cartridge svenpetersen1965 and you can find the information to build it at the following link.
This cartridge can also be used as a partition up to 3Kb for the VIC20 or as a diagnostic it needs at least 1Kb to work.
In addition to the diagnostics, you can load other roms if you use a large enough Eprom.
As an alternative to this card it is possible to build a special one which in any case must have 1Kb of RAM to be able to exclude the system one and start the program.
I haven't built this board yet but printed the PCBs, so as soon as I build it I update this article with tests.
The cables for the joystick, user port and keyboard connection are working and I tested them with the SuperExpander II
Below are the details of the cables to be made to complete the test of all the integrated.
Cassette connector, same as that of the C64
Keyboard connector
Joystick connector
User-port connector with connection for the serial cable to also test the disk port.
Also watch the video to see how these tools were used.
