2x Commodore VIC-20 – refurb and mods

… or two VICs goes SD

INTRO

Some time ago, my friend Wendell asked me to refurbish and arm two VICs with SD2IEC readers.
I’ve bought two machines in an unknown state … as usual 🙂
To my surprise, both machines were in a working state but needed a small dose of refurbishing :>




/INTRO

VIC-20 no.1

Flaws:

  • scratched case
  • missing label
  • missing key
  • damaged wire inside

As usual, I’ve started with gathering missing parts, disassembly and cleaning.






That was followed by cleaning a PCB and sorting out dirty edge connectors. I’ve also secured a damaged wire by putting it inside a heat shrink tube and covering a whole wire with isolation tape.






Wendell asked me to install a switchless kernal changer in this VIC.
The idea was based on this excellent article. I’ve grabbed an original JiffyDOS kernal license from Retro Innovations, combined jiffy ROM with a stock OS and burned it to a flashrom. However, flashrom that I had on a shelf was a bit bigger(28 PIN) than the original ROM packaging(24 PIN), plus, it was supposed to be switchless. I’ve figured that I can make an adapter out of sockets and mount a smaller chip inside. I didn’t have a ready PCB for it but I’ve figured that I can get away with a ninja-spider-soldering hack!
28 to 24 pin adapter schematics can be easily found on the internet.
The chip that I’ve used was 74LS74 – DUAL D-TYPE POSITIVE EDGE-TRIGGERED FLIP-FLOP

When all connections were soldered and ready, I’ve poured in hot glue to hold it all in place. Yeah, I know, it looks nasty but worked like a charm 🙂
Here is how it looked.









Connecting it all to R16 and Pin 34 of 6522 finished the job.
To switch a kernal “RESTORE” button has to be held while booting and viola! …. and yeah, I’ve straightened that keyboard pin header later on ;>


Next step was about installing SD2IEC because WHY NOT? :>
I’ve created my own layout of this handy device.
You can get one through an online store here

Here is how it was done.


I’ve mounted it on a back of the machine, on top of cartridge port cover.






Final pics






Adding brand new labels made by RetroKlinika




aaaaaaaaaand first unit sorted


VIC-20 no.2

Flaws:

  • missing key
  • a bit dirty and yellowed case

The second unit was slightly different because of the larger/older mainboard.

It was a bit easier with this one since it wasn’t that dirty. Actually, mounting SD2EIC was the most time-consuming part of this refurbishment/mod. I’ve skipped pics of disassembly/cleaning this time.




I started off with SD2IEC. I wanted to mount it in a similar way as in VIC no.1 but that large black radiator was preventing an easy connection. I had to prepare slightly bent pin headers for LED and TACT switch and I must admit that did the trick nicely.

I’ve also soldered a socket for eventual ROM mod in future.

Small check if SD2IEC works


aaaaand the second unit ready!


Final story

Actually, there is a story behind the second VIC-20.
Wendell wanted one of VICs for himself and the second unit for The 8-Bit Guy
as a gift, for his excellent work on covering retro computer topics and to help him with Commodore history saga on his YT channel.
I was like! OMG great idea and decided that I’ll share costs of this unit.
The 8-bit Guy responded that he already owns a few VICs and that he simply doesn’t have room for another unit.
Wendell suggested that maybe another awesome YouTuber would like to get it – Nostalgia Nerd
The funny part was … actually, watch it yourself 😉

OUTRO

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