The sun is frowning at me while I go out for a walk...

OK, this is not about my usual circuits, but had the chance to go to a today, and found a nice collection of works by and a by .
Nothing great, but two nice

This is the original board I modeled my clone after. I bought it as broken, but did not care much as I just needed measurements and to clear up some part of the schematics.
Turns out the issue was only a scraped trace on the backside, that shifted and touched a nearby via.
This was just dumb luck.

First rendering of the card clone. Still a few things to fix/optimize before I can send the first to print, but it's progressing well.

After a week and doing it in small breaks, I finished probing this board and I've redrawn the schematics in . Will soon start to design its clone (with some slight improvements).

Just because otherwise I'm going to forget about it, here is my PCB for the AT2XT project.

I needed something different than the one offered at the project's page. Use it if you need it

Time to order some more
This time it's another with an ES688 plus a real onboard and something a bit more trivial: a small with a that plugs on the joystick port.
There are already similar projects, but I wanted one that was relatively easy to solder with my instrumentation (and also wanted to experiment).

I also ordered the new revision of my Redux.

Wow, did not know that there were modern patches to add composite mode to games. Here you can see a SCI driver I found at Vogons and a patched 4.

Two examples of VS RGBI on my Redux. This board is built with "new" style composite output, which saturates the colors a bit more than the "old" style.

I should really repair my Commodore 1084 for these tests, but for now this sucky flat TV will do.

I'm going to design another revision of the Redux card, so that it can be built with the "old" style composite output without having to cut traces. This will allow less saturated colors from the composite output.

The idea is to allow people to build the card with the output style they like.

Ok, I'm enthusiastic!
I finally drilled the bracket for my Redux board and fitted it on the 5160 XT .

I threw at it CheckIt diagnostics, and even demo... and everything worked! Even the "Trace the beam" section of the !

Sorry for the colors that might be a bit too vivid, but I used a composite->vga converter that is old and crappy.

I've updated the repo with the results

OK, just set the for the Redux to public.
I will continue the development out in the open.

It's a clone (or an attempt at one) of the original Color Graphics Adapter card.


I also need to replace the 74LS174 I used with proper 74S174, like on the original board. I also need to swap the VRAM with chips that have at least 120ns as access time. The current ones are at 150, unlike my original.

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hkz boosted

hello everynyan!!

for two years i've been developing a project known as MegaGRRL. it's a portable sega genesis music player that uses the original sound chips, and plays VGM files from an SD card.

the portable version is still in development, but recently i designed a simplified, desktop version of the player, and i'm happy to announce that the schematic, PCB, firmware, and 3d print design files for MegaGRRL Desktop are now available for anyone to build.

if you're an FM synth nerd or just a fan of chiptunes, check it out!

longer demo video on youtube: page:
world wide web site:

It's interesting that the Micro8088 misdetects it (it says that there is a video bios present). But it does absolutely the same thing with the original card I have here.

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Set the repository of my to public!

Keep in mind that this board is still undergoing basic testing, but I had joystick / FM / Digital audio working just fine on my 286 test machine.

Will install it in my Micro8088 build later/tomorrow.


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