... or two VICs goes SD
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 :>
- scratched case
- missing label
- missing key
- damaged wire inside
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 a 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 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 https://www.retro-cloud.eu
Adding brand new labels made by RetroKlinika
- 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.
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 ;)