Denial

Not an expert but I would not think taking Y/C directly from the chip will work. I would guess Q2 and the biasing network was put in there for a reason.

This one springs to mind (a bit old) http://www.zimmers.net/anonftp/pub/cbm/vic20/programming/vic20frontiers.txt The author (Viznut) also made the famous (?) "Impossiblator 3" demo. Some bits were discussed here recently (well some years ago now :) http://sleepingelephant.com/ipw-web/bulle...

Thanks, so this appears to be some kind of official thing.
But what are the applications for this? Are there any?

Hi. I have a VIC 20 CR board with a bodge wire on the back that appears to connect the audio pin of the VIC chip to pin Y on the expansion port via a 1K resistor. What does this actually do? Are there any cartidges that use this? Do you have a picture? Somewhere I've seen a schematic this this labe...

Hi. I have a VIC 20 CR board with a bodge wire on the back that appears to connect the audio pin of the VIC chip to pin Y on the expansion port via a 1K resistor. What does this actually do? Are there any cartidges that use this? Apologies if this has been answered already, I did a quick search on h...

[...] The only bit that doesn't make sense is that X=35 input. I've simulated this and VCNT.RESET goes high when X=35 on the LAST LINE. It doesn't make sense and clearly I have to check things over a few more times and try to work out why it doesn't reset at that point on the last line. I'm going t...

Bit late to the party. It appears the S-Video mod being talked about here takes the chroma directly off the chip, albeit with a resistor + cap in between. This does not feel right to me. Should there not be a proper buffer/amplifier in between? I.e. similar to how the C64 modulator operates.

I did an audio capture of the high score music. Here are 3 waveforms from the same sample from different VIC20s (VIC20 CR model, NTSC 'old' (2-prong power), PAL old.) vicsamples.png The NTSC old model is the clear winner here with 4 distinguishable levels corresponding to 3 voices. The other models ...

If needed I can do a new capture - in theory I could also measure the phase offset between light and dark colors with my oscilloscope, although how exactly I haven't yet found out.

The order from left to right is black / white red / light red cyan / light cyan purple / light purple green / light green blue / light blue yellow / light yellow orange / light orange so then green would be at index 8 indeed. I also notice that yellow is also very greenish (compared to light yellow....

The NTSC VIC has two variations of cyan apparently. I found this post that may be related https://www.lemon64.com/forum/viewtopic.php?p=979712 My NTSC VIC cyan looks distinctly blue so I guess this is an older variant - see images from capture card (NTSC contrast is a bit off but the color should be...

Apparently early versions of the 6560 had a different palette where cyan would look more like a light blue rather than the colors described here. (I think I may have one of these.) Could be interesting to create a variant for that too.

PAL VIC-20 is 312 lines

Re cyan being off: I seem to recall that older 6560 variations generate a different cyan that is more blue-looking. E.g. this is what my NTSC VIC20 looks like bt848_ntsc_comp_vic20-ntsc.png My PAL VIC20 looks like this bt848_pal_comp_vic20.png apparently the cyan on later 6560 models should look mor...

There is some research data here (partly German) The PAL colour generation is a bit problematic because the even and odd lines have different angles/amplitudes for each of the colours. This is probably due to the way the colours are generated on the chip. In theory all dark colours (2-8) should have...