sid

21 Articles

The Commodordion Gets A Big Usability Upgrade

August 28, 2024 by 14 Comments

The chiptune scene is dominated by Game Boys and other Nintendo hardware, but one should never forget the gorgeous, beautiful tones that come from the hallowed Commodore 64. [Linus Åkesson] knows this well, and it’s at the heart of his work on the Commodordion. Now, he’s built an even better version.

The original idea he had was to build an accordion-like control surface for the SID chip in a Commodore 64. The device is capable of creating beautiful accordion-like music with a simple 8-bit flair. He has since dubbed the original Commodordion the “bass Commodordion,” while the new version is classified as a tenor instrument.

The prime upgrades are ergonomic. The previous instrument was too heavy, with the left hand having to carry an entire Commodore 64 on its own. It was also hard to reach the keys. The new version is much lighter, with one of the two C64s of the original having been removed. The supporting electronics have been redesigned to more neatly fit into a space behind the bellows.

The result is a machine that’s far easier to play, and one that won’t injure the user in extended play sessions. “It’s now a pleasure, not a pain,” says [Linus]. The payoff in usability is obvious, and the tunes themselves are hauntingly beautiful.

We first covered the Commordordion back in 2022, but it wasn’t the first time we saw one of [Linus]’s impressive creations.

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Two circuit boards with bright seven segment displays

Retro Stereo SID Synth Looks And Sounds Sensational

September 10, 2021 by 36 Comments

Over the years, plenty of work has gone into emulating the Commodore 64 6581 SID chip, but as [SlipperySeal] puts it, nothing beats the real thing. His take on the MIDI SID-based synth not only sounds fantastic, but looks the business.

The 6581 SID arguably blessed the Commodore 64 with some of the best sound capabilities of any home computer in the 8-bit era (make sure to ‘sound off’ in the comments if you disagree). The 6581 was a three-voice analog synth with a dizzying array of settings. This was at a time when most home computers could just about manage a ‘beep’ of varying lengths and frequencies.

When you mix MIDI with the capabilities of the SID, you get something like [SlipperySeal]’s awesome looking synth, known as ‘Monty’. While the road to this point unfortunately resulted in several blown-up SID chips, the sacrifice seems to have paid off.

Realizing the limitations of having ‘just’ three voices, Monty is designed to use two SID chips in parallel, for a total of six voices in pleasing stereo sound. MIDI commands are transferred to the dual SIDs by way of an ATmega1284p microcontroller. The SID is well understood by this point, and [SlipperySeal] goes into great detail explaining the fundamentals of SID programming over on GitHub.

This isn’t the first MIDI synth that is based around the C64 SID chip, but [SlipperySeal] made sure that his stood out from the crowd. The seven-segment display centered on the board makes for a delightfully simple visualizer, an effect that looks even better when running two Monty boards at once, each responding to alternate MIDI channels (check out the video below). Naturally, we’re also fans of projects that include ominous, cryptic keyswitches.

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Dial-a-SID Is A Glorious Chiptune Jukebox

July 8, 2021 by 8 Comments

Old-school rotary telephones aren’t particularly useful for their original intended purpose in this day and age, but they’re great fun to hack into new projects. [Linus Åkesson] has done just that, with his Dial-a-SID jukebox build. (Video, embedded below.)

The build installs a Raspberry Pi 3 inside the body of the telephone, running a SID chip emulator and loaded up with the High Voltage SID Collection. The Pi inside outputs sound to an external stereo system for playing chiptunes at a party.

The real party piece, however, is that the handset can be lifted and the telephone dialled in order to listen to and select tracks for the playlist. Tracks can be selected by individual codes, by composer, or even by year. In the event the playlist grows empty, the default behaviour can be set to keep playing random tracks in the meantime.

With over 2000 hours of SID music inside, it’s unlikely the Dial-a-SID will run out of tunes anytime soon. We’d love to see a similar interface used for a jukebox hooked up to a modern streaming service, too. If you build one, let us know! Alternatively, consider hooking up your rotary phone to your smartphone. Video after the break.

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Sad Without A SID? This Comes Pretty Close

July 24, 2018 by 36 Comments

The MOS Technologies 6851, popularly known as the SID, is a legendary sound synthesiser integrated circuit from the early 1980s that is most famous for providing the Commodore 64 home computer with its ability to make noise. At the time it was significantly better than what could be found in competitor machines, making it a popular choice for today’s chiptune and demo scene artists.

There’s a snag for a modern-day SID-jockey though, the chip has been out of production for a quarter century and is thus in short supply. Emulation is a choice, but of little use for owners of original hardware so it’s fortunate that [Petros Kokotis] has produced a SID replacement using a Teensy 3.6.

The operation is simple enough, the Teensy provides all the requisite SID data lines via some level shifters for the host microcomputer, and uses [Frank Boesing]’s ReSID library to do the heavy lifting part of being a SID. You can download the code from a GitHub repository, and he’s posted a video we’ve put below the break showing a prototype in action with a real Commodore 64. The audio quality isn’t brilliant due to a phone camera recording from a very tinny speaker, but notwithstanding that it has the air of the real thing.

This isn’t the first SID we’ve seen here. How about a MIDI synth using one?

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Emulating A Complete Commodore 64

March 28, 2018 by 40 Comments

When the Commodore 64 was released in 1982, it was a masterpiece of engineering. It had capabilities far outstripping other home computers, and that was all due to two fancy chips inside the C64. The VIC-II, the video chip for the C64, had sprites and scrolling, all stuffed into a single bit of silicon. The SID chip was a complete synthesizer on a chip. These bits of silicon made the C64 the best selling computer of all time, but have also stymied efforts to emulate a complete C64 system on a microcontroller.

[Frank Bösing] has just managed to emulate an entire C64 on a Teensy 3.6. The Teensy uses an exceptionally powerful microcontroller, but this is a labor of love and code.

The inspiration for this project comes from a reverse-engineered SID chip that was ported to the Teensy 3.2. The SID chip is the make it or break it feature of any C64 emulation, but the Teensy 3.2 didn’t have enough RAM for the most recent versions of reSID. With the release of the Teensy 3.6, [Frank] figured the increased amount of RAM would allow a complete C64 system, so he built it.

The new C64 emulator uses a Teensy 3.6, with a small add-on ‘shield’ (or whetever we’re calling them) to provide connectors for joysticks and the Commodore IEC bus. There’s audio out, support for USB keyboards, and support for an IL9341 SPI display or a regular ‘ol VGA display.

The entire development of this Commodore emulator has been documented over on the PJRC forums, and all the code is over on GitHub. It’s a fantastic piece of work, and as the video (below) shows, this is a real Commodore 64 that fits in your pocket.

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Giving The World A Better SID

November 24, 2016 by 60 Comments

Here’s a business plan for you, should you ever run into an old silicon fab sitting in a dumpster: build Commodore SID chips. The MOS 6581 and 8580 are synthesizers on a chip, famously used in the demoscene, and even today command prices of up to $40 USD per chip. There’s a market for this, and with the right process, this could conceivably be a viable business plan.

Finding a silicon fab in a dumpster is a longshot, but here’s the next best thing: an FPGASID project. The FPGASID is a project to re-create the now-unobtanium MOS 6581 found in the Commodore 64.

The Commodore SID chip has been out of production for a while now, and nearly every available SID chip has already been snapped up by people building MIDIbox SIDs, or by Elektron for their SidStation, which has been out of production for nearly a decade. There is a demand for SID chips, one that has been filled by “clones” or recreations using ATmegas, Propellers, and nearly every other microcontroller architecture available. While these clones can get the four voices of the SID right, there’s one universal problem: the SID had analog filters, and no two SIDs ever sounded alike.

From the audio samples available on the project page for the FPGASID, the filters might be a solved problem. The output from the FPGASID sounds a lot like the output from a vintage SID. Whether or not this is what everyone agrees a SID should sound like is another matter entirely, but this is the best attempt so far to drag the synth on a chip found in the Commodore 64 into modern times.

The files, firmware, and FPGA special sauce aren’t available yet, but the FPGASID is in alpha testing, with a proper release tentatively scheduled for early 2017. Maybe now it’s time to dig out those plans for the Uber MIDIbox, with octophonic SID goodness.

A Raspberry Pi SID Player

February 6, 2015 by 26 Comments

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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