You might remember me from the introduction thread I made last month. This is going to be the project thread for my Creativision clone build, which I've chosen to call the "Derivavision."
I will also be tracking the development in more (some would say too much) detail on the Leaded Solder blog – probably the first blog post on this will be early July as I tend to procrastinate on editing.
Here's the constraints I've set out for myself at the moment:
- NTSC TMS9918A for the VDP, since I have a lot of them and I live in Canada;
- Composite output, no RF;
- Plays retail cartridges;
- Single-voltage USB power supply (with optional connector to inject other voltages if the cartridges/tape interface needs them;)
- No controllers or keyboard yet because I don't quite understand the matrix;
- Open-source everything as soon as it starts to work.
As of about ten minutes ago, after some debugging and bodge-wiring, the Derivavision has run through a couple cycles of the attract mode of Sonic Invaders (see below.) Thank you very much to Cheshire Noir for providing me with a copy of the game, as otherwise I'd still be hunting eBay for one.
Please don't mind the awful colours; the green gun on my test PVM has essentially died at this point. As you can see from the stickers on the front, this thing has seen tens of thousands of hours in broadcast television.
So far the bodge list is relatively minimal, although I am noticing that the video output on this system is much worse than on my Sega SG-1000 clone or ColecoVision clone despite having "sort of" the same output circuit. Cleaning up the luminance ringing and some other colour issues will be worked out in the next few weeks (I ran out of ferrite beads so things are sort of jumpered-together; I think the jumper is causing interference issues.)
Please check out the GitHub repository here, although I don't recommend you actually build one for yourself yet, at least not until the keyboard/controller interface is figured out. The attract mode on Sonic Invaders isn't that much fun to watch.
Thanks everybody! I will update this thread as more progress is made.