MIDI synth control of Atari 2600 sound chip (TIA)

Sort of like synthcart, only with more synth and less cart! Less hacking/drilling a vintage VCS, too.

After months of distraction I finally got around to implementing: 1) my own clock so I don't need an Atari MB, and 2) MIDI control. Laughably enough, it took me like 2 hours, so it was a welcome break from banging my head against other projects for days straight. I'm quite pleased with the results! Still would like to add a couple features but this is enough to run genuine "Atari sounds" off my sequencer... good enough for government work, as they say!

Ignore the JX-3P and PG-200 in the background, those are for another project that I'll stick up in a couple weeks. :)

Also please ignore the distortion and amount of times I say "um." I'm still getting used to recording myself.

Questions welcome! Enjoy!

PS: It pains me to use the tags "circuit" and "bending" just because I hate that cliche so much. Plus that crowd seems to more enjoy glitching known hardware rather than building predicable stuff from scratch. Still, hopefully it will be, as the internet says, relevant to their interests.

Category:

Music

Tags:

• atari
• 2600
• tia
• midi
• synth
• circuit
• bending

[aadz93]

hey i wanted to know if i could use a Siemens SAB8088 8-bit microprocessor for this

project? its a 40-pin chip in a DIP package. please replay

[TheMindOfPat]

@aadz93 "Could" is a great word. :) Microcontrollers usually have built in memory, UARTs, and direct I/O pins (you need about 12).  Motorola, Microchip, Zilog, Intel 8041, etc, are examples for the US.

I'm not familiar with the SAB8088 but I would not recommend a "microprocessor" unless you really know what you're doing. But sure, that's how Atari did it.

A lot of things are "possible," just check the datasheets of the components to make sure you know what you're getting yourself into. :)

[aadz93]

@TheMindOfPat oh ok but will a basic stamp microcontroller work?

[TheMindOfPat]

@aadz93 I've never personally used BASIC stamps, so I can't say for sure. BASIC may limit your baud rate choices (MIDI is not a standard PC rate), and may be slow-ish for I/O control depending on your clock speed, so be careful of that. Check the timing diagrams in the back of the TIA / Stella prorgammer guide if you're curous.

[aadz93]

sorry I know its been a awhile but will this microcontroller work. it is a toshiba 47c440 4-bit microcontroller ( its the only one that i could find in my house) and i can send you a datasheet of it

[aadz93]

how i found this microcontroller in this robotics kit and its a ATMEL AT91SAM7S256

microcontroller will this work?

[TheMindOfPat]

I can't seem to post links into youtube replies, but search "electrical specifications for midi" for HW info, and the gweep result for "the midi specification" seems pretty thorough for protocol info. Or just search midi protocol, midi spec, midi circuits, etc. It's really not that bad of an interface. Good luck!

[G0ggleblind]

Ahh I see you make a good point. I'm not too versed on how these things work but would like to know. I checked out the TIA pinout, the Stell aprogramming guide and have a small asm program to create sound in Stella.

Do yo uhave any suggestions on we sites that will explain MIDI interfacing in simple terms?

Thanks

[TheMindOfPat]

Having a PC drive it directly via a parallel port? It might work. I think it uses about 11 data lines at 1.19 MHz. Slower "may" work. See if you can use EPP and force some of the status pins to be data. You will have to do some discrete electronics and write your own device driver.

On the other hand, for a couple bucks you can get a microcontroller and interface via serial, standard parallel, USB, MIDI, or whatever!

[G0ggleblind]

Hmm is there a way to patch teh TIA into a computer's printer port?