tonyrocks wrote:I would love to be more confident in my skills of soldering, but as I've gotten older, my eyes and steady hand are not as good anymore. I don't have my original Vic-20...which I did actually get in 1983 for Christmas as well But mine was DOA when I opened it Christmas morning, and had to wait until the following day to return it and get another. I do wish I still had it though.
However, I still have and use my Commodore 128 that I got for Christmas i think in 1986. I want to start modding it, but again, I'm not confident. For now, I will use my SD Card and also my Wifi Modem to telnet to BBS.
In all seriousness, I totally admire your custom mod work for Vic-20, which always takes me back to 1983, when I would have a blast playing Radar Ratrace and OMEGA race.
No worries!
Anyhow, the mod came for me as a natural consequence during the graphics project I did together with tokra mainly from 2010 to 2013. It just happened all the pieces fit together: an already working display routine (a.k.a. graphics card driver ) and a converter on the PC for photographic images which "just" needed to be expanded from 72 to 208 horizontal pixels. Then, the hardware mod just begged me to bring it into existence.
If we happen to meet up at any time in the future, I think we ought to drink a beer (or any preferred beverage of yours) together.
Oh, I haven't been so active here lately, but that was an interesting mod. From the pictures it looks like he is using a Motorola 6820 and lots of discrete logic chips. The memory addition is just a bunch of HM6116 (2KByte) chips. And he put in his own power supply which looks quite nice.
From my guessing (as I don't have any schematics or wiring to go from) he is probably using the 6820 for output and generating the 40/80 column screen signal from that in some way. It is probably monochrome as 80 column would require that. I can also barely see a chip that looks like a EEPROM with a label on it, so there is some code in there. I have no idea how the code to get 80 columns from a 6820 would look like.
In the video the new owner tells the VIC-20 in this setup was left in its original state, not modified at all. There's just this heavily customized cartridge expander on the outside which does the job.
Nevertheless, what was done there remains an impressive wire-wrapped construction.