SID Organ Pulls Out All the Stops

Someone left this organ out in the rain, but [Tinkartank] rescued it and has given it a new life as a SID controller. What’s a SID, you ask? That’s the sound chip Commodore used in the C64, a remarkable chip revered among retro gamers that was way ahead of its time.

He threw out everything but the keyboard assembly for the build. Each key press now drives a momentary button, and those are all wired up to an Arduino Mega through some I/O expansion boards left over from another project. The Mega drives the MOS6581 SID chip which generates those sweet chiptunes. There are four CV outs for expanding the organ’s horizons with Eurorack modules.

Our favorite part is the re-use of the stop knobs — particularly that they are actuated the same way as before. The knobs still technically control the sound, but in a new way — now they turn pots that change the arpeggio, frequency, or whatever he wants ’em to do.

The plans for the future revolve around switching to a Teensy to help out with memory issues. Although it’s a work in progress, this organ already has a ton of features. Be sure to check them out after the break.

Once you dive down the chiptunes rabbit hole, you might want to take them everywhere.  When you get to that point, here’s a portable SID player. A SIDman, if you will.

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A Raspberry Pi SID Player

Of all the vintage chiptune machines out there, the Commodore 64 is the most famous. Even 30 years later, there are still massive gatherings dedicated to eeking out the last cycle of processing power and graphics capability from the CPU and the infamous synth-on-a-chip, the SID. [Bob] wanted to build a SID jukebox. A C64 is capable of the job, but if you want to have every SID composition on an SD card and connect that to a network, a Raspberry Pi is the way to go.

The SID chip, in its 6581 or 8580 versions, is controlled directly by poking registers on the chip through the address and data busses. This means a lot of pins, too many for the original Raspi expansion header. That’s not a problem that can’t be solved with a few shift registers, though. The rest of the circuit is an LM386 audio amplifier, an LCD that displays the current song, and a can crystal oscillator for the SID.

Right now everything is wired up on a breadboard, but making this a Raspberry Pi hat would be a rather simple proposition. It’s only a matter of finding a SID with working filters, and if you can manage that, it’s a pretty easy build to replicate. Video below.

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