(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.
Fresno Commodore User Group