… or two VICs go 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 working but needed a small dose of refurbishing :>
- scratched case
- missing label
- missing key
- damaged wire inside
Switchless kernal changer
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, the 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 used was 74LS74 – DUAL D-TYPE POSITIVE EDGE-TRIGGERED FLIP-FLOP
When all connections were soldered and ready, I 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 ;>
The next step was about installing SD2IEC because WHY NOT? :>
I’ve created my layout for this handy device.
You can get one through an online store here
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.
I started with SD2IEC. I wanted to mount it similarly as in VIC no.1 but that large black radiator was preventing a nice placement. Instead, I prepared a slightly bent pin header for the LED and the TACT switch and I must admit that did the trick nicely.
A socket was soldered on for eventual ROM mod in the future.
There is a story behind the second VIC-20.
Wendell wanted one of the 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 the Commodore history saga on his YT channel.
I was like! OMG great idea and decided that I’ll share the 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
Just watch it yourself 😉
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