6502.org

Looks great Rich! I'm glad to see my Kicad schematics turn into a real working board! Well done!
Sorry about the transcription error. As usual I have too many project ideas and not enough time to complete them.

Steve

Thanks Steve! It has been a great project to work on. I only regret wasting a year noodling over why I had screen corruption. What triggered my re-examination of the schematic was a video I saw on YouTube, and then I started digging. Also didn't help that I also had a corrupted CHRGEN ROM (not sure how that happens with a mask ROM, but whatever).

I created a GitHub repro for it (https://github.com/RichCini/VIC-20-Reloaded) so people can take a look. The final size is just a tad bigger than S-100 size (10.375" x 5.375") which is smaller than the keyboard. So, it's not really designed to be a stock replacement, but something smaller. Plus, you can use a PS/2 keyboard with it if you use one of the external matrix encoder boards from Jim Brain (although I haven't tried that).

I ordered a third prototype run this week to make sure it's all works as expected, but the schematic changes between revisions are very minor (fixing the RAM R/W and adding two fuses).

Enjoy.

Rich

P3 prototype arrived last week. Naturally there is one small error that is fixed by two cuts and two jumpers (D4/D5 crossed). Otherwise, seems to work fine. I will be doing a 4th run at some point because I just added an S-Video modification which can be used with the stock DIN5 (based on http://sleepingelephant.com/denial/wiki ... deo_output) -- two components and three jumpers.

After this, there's not much more I can squeeze. I thought about adding two mounting holes to support the matrix keyboard encoder. Might still do that.

Rich

All --

Just a quick update. I ordered a version of the board with the user port edge connector and it works just fine, other than two data bus lines swapped (fixed with two cuts and two jumpers; Revision D).

I did another respin (not ordered yet, Revision E) that includes that fix, an extra mounting hole, and a mod for separating chroma from luma (a popular mod for the VIC) that requires three jumpers. Steve is independently building the D-revision to see if there are are any "buildability" changes needed.

I've tested the board with the Retro Innovations PS2-to-matrix encoder and that works as well. I don't use it regularly, but its something I wanted to test.

More to come...

Rich

More projects being worked on (untested as of now; files on my Github repro):

VIC-1214 speech synthesizer. I can't find any info on the original, so I used the number for my re-do of an SP0256-AL2 based board I made in 1981. While it has edge fingers, it's designed to solder an EDAC edge connector to it.

VIC-1005 3-slot expansion board. Uses separate header from backplane to accommodate vertical cartridges.

Enjoy

Rich

Sorry, please excuse my ignorance (and I am supposed to be working at the moment ).. What's the difference between the Vic2020 (Dan Werner) board and Vic20 Reloaded (RichCini) board? Is one a derivation of the other?

The main reason I've started sniffing around these 2 projects is because I was wondering if there was a small/modern Vic20 PCB available. I'd like to have a go at making a Vic chip replacement of my own.. but I need other bits an pieces to be working well. I have 3 dead Vic20s (all have dead Vic chips) but I'd prefer something smaller that will happily run of 5V and not take up heaps of space on my desk.. and smaller also means cheaper PCB production and shipping too.

Maybe even modifying an existing schematic/board may help me since I could add some additional header pins or whatever.

I know others have looked into the whole FPGA Vic replacement but it's something I've wanted to have a go at (hobby-wise) for quite some time

They’re the same in the respect that they’re both VIC-20 recreations. I believe Dan’s is full size and mine I tried to get into an S-100 card size (10” x 5”). I eliminated the cassette interface due to the smaller board size but I left a header so you could make a dongle for it if needed. My test board at home uses Dan’s keyboard re-creation.

Aha! Thanks Rich. That explains why I saw the Vic2020 keyboard in your photos There must be a third new motherboard incarnation - I'm sure I saw RetroShack or Jan Beta on YouTube building a blue PCB that was almost identical to the original CBM CR one.

I might give your board a go then Rich if it's smaller. Is it happy with the WDC65C02?

There’s at least one other clone out there. I did mine as more of a “how small can I get it” yet keep the flavor of the original. I could probably squeeze it tighter but then connector spacing and stuff would be off. I didn’t design it to be out in a VIC case otherwise it would be 14” long.

I don’t remember which CPU I have in mine; I’d have to look at a picture. If it has the C02 in it, there have been no issues.

Rich

Finding new 1k x 4 RAM chips is going to be a challenge for me - I don't really want to buy second-hand/old ICs (probably expensive too). I got loads of new 8k RAM chips sitting in a drawer.. but I don't really want to mess with the design too much (and they're a bigger footprint too). I don't suppose you or anybody else has an alternative to the 2114 chips? Maybe I will have to go down the route of using 2 8k chips instead. Mmm.

Update: Actually.. I see Dan's design uses one 128k chip. That may be the way to go - take that design and see if I can squash the size like yours.

I used the VIC-20CR (“cost reduced”) as the model and I think that used higher density RAM rather than the 2114’s. But it’s been a while since I looked at the schematic.

This is legendary! Well done!

Thank you very much!

Rich