Thursday, 5 April 2012

VIC-20 Diagnostic Cart




(photos courtesy of Ray Carlsen)
Yesterday master C= technician Ray Carlsen demonstrated the CBM VIC-20 Diagnostic cartridge on a later VIC-20 board. He connected the special VIC-20 Diagnostic harness to the computer and ran the tests. The photos show some of the test screens. When a keyboard dongle was attached, the cartridge report that the keyboard was bad. With the dongle removed the keyboard was reported as being good. When a C64/128 Diagnostic harness was used with the VIC-20 Diagnostic cart, the tests would run to a certain point and then lock up the computer. In other words, that C64/128 harness was not meant to be used with the VIC-20 Diagnostic cart. Ray has information on the Diagnostic cart at http://personalpages.tds.net/~rcarlsen/cbm/misc/diagcart/vic20%20cart/ He has not yet posted a schematic of the VIC-20 Diagnostic harness nor its user port cartridge.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

3 comments:

  1. Since I posted the link on Denial, I reverse engineered the VIC-20 dongles from the code. They do all work, including the keyboard one. As I also have the c64 ones, they are quite different. I'd be interested to see how mine differ from the schematics of the 'real' one that Ray has.

    Rob

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  2. We could not identify the keyboard dongle; it may have been a C64 keyboard dongle. The C128 keyboard dongle is definitely different (and still doesn't work right with the C128 Diagnostic cartridge). The rest of the VIC-20 Diagnostic harness (with its user port cartridge) works perfectly.

    Truly,
    Robert Bernardo

    ReplyDelete
  3. Rob, because you having a working VIC-20 keyboard dongle, can you send that information to Ray Carlsen?

    Truly,
    Robert Bernrdo

    ReplyDelete