VIC-20

Here are some basic scope captures of the VIC-20. This is off of a machine that does not work. I will post another section if I can get it working!!

FB4 and FB5, clocks entering the VIC-1.

FB10 and FB11 Clock exiting the VIC-1 and the inverter UB4.

VR/W (Pin 17 of the expansion connector) and VA0/Pin 21 of the VIC-1. Hold your tongue just right, because the goes away when I tap on UD7.

R10 Test Point, or Video out. I caught this when the VIC-1 was spewing out random text and graphics on the screen. This does tell me that a whole bunch of stuff was working at this point though, as this is what a standard NTSC display should look like.

Pin 1 UF8 (CR/W) is the yellow trace. FB11 is the blue. The machine is now working (R15 was open).

Pin 12, UC2 (VR/W) is the yellow trace. FB11 is the blue.

Pin 21, UB7 (VA0) is the yellow trace. FB11 is the blue.

Pin 9, UB7 (BD7) is the yellow trace. FB11 is the blue.

Pin 9, UD9 is the yellow. FB11 is the blue.

Pin 10 UD1 is the yellow. Pin 11 UD1 is the blue.