Ok, this is my lastest VIC-20 dream, part of a lot bigger dream.
I was by a friend of mine house, with my own VIC-20 (white shining keys due to being washed in a dishwasher), C2N, 8K expansion and TV-set. The house was very busy with many other friends coming and leaving (like in a college).
I had with me some old strange yellow tapes, given to me by the late uncle of one the friends that were there.
Not knowing about these tapes, I tried to load them into my VIC-20. I put one into the C2N and typed "LOAD". With a big surprise, the VIC20 started to play an episode of "Happy Days" (the tv serie). Wow! Vic 20 was doing video-playback!
The loading continued for long time, and the VIC continued to play what seemed to be a TV channel. At a certain point it started reproduce an episode of "Little Britain", in the part when the background voice says "Britain, Britain, Britain ...".
I was really surprised by what the VIC was doing and was struggling to understand how it was done. I figured that they had compressed the whole video in 8K ram space, since I was unsing an expansion. But even in the dream this seemed unrealistic, mostly because there were no sign of compression artifacts. I even phoned a fictional Commodore help-desk to ask for explanations. But no clues.
At a certain point the "Little Britain" voice materialized entering the room and I was distracted talking with him. We talked about Kenny Craig, the stage hypnotist, being my favourite character in that serie.
Then I resumed my quest for understanding the magic of video playback. It was really intriguing. By messing with run/stop and with C2n's stop/rew/play, I noticed that the video playback was coming directly from the tape and not from VIC20, that is, the video signal was actually recorded on the tape.
At first I was disappointed because video playback was not a feature of my VIC20. What a delusion. But then I started again to wonder about how it was actually done. I knew that video signals could not be recorded directly on tape because they are high in frequency. I knew that well because I had tried that in my childhood, without success.
Looking at how the cable were connected I eventually realized the trick: the audio signal from the tape was mixed with the VIC-20 video signal and then feed to the TV set.
I figured out that the VIC20 signal acted as a "carrier" and the tape signal as the "modulated" signal containing the real information. I also realized that in order to make it work properly, the VIC-20 had to display a completely white screen, thus avoiding any "ghost" images.
Indeed, the owner of the tapes, had put a small stub program at the start of each tape that made VIC20 go on white screen before of the video playback.
This way he was using VIC-20 as a VIDEO TAPE RECORDER!
I briefly checked all the tapes and, alas, they were all video recordings and not VIC-20 games as I had hoped. (But my disappointment changed when I discovered a porno at the end of a tape! eh eh!

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