A man playing an accordion-like instrument made from two Commodore 64s

The Commodordion Turns Two C64s Into A Single Instrument

October 22, 2022 by Robin Kearey 16 Comments

One of the main reasons the Commodore 64 became an icon of the 1980s was its MOS 6581 “SID” sound chip that gave it audio capabilities well beyond those of other microcomputers of the 8-bit era. The SID became something of a legend by itself among chiptune enthusiasts, and several electronic instruments have been designed that generate their sound through a SID chip. Not many of those look anything like traditional musical instruments however, so we’re delighted to see [Linus Åkesson]’s new project: two Commodore 64s joined back-to-back using a bellows to form a wonderful new instrument called the Commodordion. It can be played in a similar way one plays a traditional accordion: melodies are played with the right hand, chords with the left, and volume is adjusted by varying the pressure in the bellows.

The two computers are basically unmodified, and boot Commodore BASIC like they normally would. A custom circuit board emulates a cassette player and provides the software to be loaded into memory. Both computers run the same program and can be switched between the right-hand and left-hand role by pressing a specific key combination. The software in question is called Qwertuoso, and basically maps notes and various features of the SID chip to keys on the Commodore’s keyboard.

Of course, it’s the bellows that makes this instrument a true member of the accordion family. Made from 5.25″ floppy disks and sticky tape, it forms a more-or-less air-tight system linking the two computers. The airflow in the bellows is measured through a microphone placed next to the air intake: the amount of noise generated is roughly proportional to the amount of air being expelled or inhaled. This information is then used to modulate the volume generated by the two SID chips.

By [Linus]’s own admission it’s not the most ergonomic of instruments, so we’re doubly impressed by the amount of skill he demonstrates while playing it in the video embedded below. It’s not the first time either that he has turned a Commodore 64 into a musical instrument: he previously built a church organ and a theremin. While the Commodordion may look complicated, it’s actually much simpler in construction than a mechanical accordion.

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A schematic explaining the workings of the Commodore 64's joystick port

Bluetooth Interface Adds Rumble Feedback To Commodore 64 Games

October 8, 2022 by Robin Kearey 6 Comments

Nothing says “1980s gaming” like a black joystick with a single red fire button. But if you prefer better ergonomics, you can connect modern gamepads to your retrocomputers thanks to a variety of modern-to-classic interface adapters. These typically support just the directional pad and one or two action buttons, leaving out modern features like motion control and haptic feedback.

That’s a bit of a shame, because we think it would be pretty cool to feel that shock in our hands whenever Pitfall Harry drowns in quicksand or Frogger gets hit by traffic. We’re therefore happy to report that [Ricardo Quesada] has decided to add rumble functionality to the Bluetooth-to-Joystick-port interface that he’s been working on. He demonstrates the feature on his Commodore 64 in the video embedded after the break.

Naturally, any software needs to be adapted to support haptic feedback, but a trickier problem turned out to be the hardware: joystick ports are input-only devices and therefore cannot send “enable rumble” signals to any connected gamepads. [Ricardo] found a clever way around this, using the analog inputs on the joystick port that were typically used for paddle-type controllers.

The analog-to-digital converter inside the computer works by applying a pulse signal to the analog port and measuring the time it takes to discharge a capacitor. The modern gamepad interface simply detects whether these pulses are present; they can be enabled or disabled through software by toggling the analog readout on the joystick port. This way, the joystick port can be used to send a single bit of information to any device connected to it.

[Ricardo] developed patches for Rambo: First Blood part II and Leman to enable rumble functionality. He describes the process in detail in his blog post, which should enable anyone who knows their way around 6502 machine code to add rumble support to their favorite games.

The adapter works with a variety of retro systems that use the Atari-style joystick interface, but if you’re an Apple II user, you might want to look at this Raspberry Pi-based project that interfaces with its nonstandard joystick interface. If you’re into wireless gaming in general, be sure to also check out our history of wireless game controllers.

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C64 Turned Theremin With A Handful Of Parts

August 30, 2022 by Lewin Day 7 Comments

The theremin is popular for its eerie sound output and its non-contact playing style. While they’re typically built using analog hardware, [Linus Åkesson] decided to make one using the venerable Commodore 64.

The instrument works by measuring the capacitance between its two antennas and the Earth. As these capacitances are changed by a human waving their hands around near the respective pitch and volume antennas, the theremin responds by changing the pitch and volume of its output.

In this case, the humble 555 is pressed into service. It runs as an oscillator, with its frequency varying depending on the user’s hand position. There’s one each for pitch and volume, naturally, using a clamp and spoon as antennas. The C64 then reads the frequency the 555s are oscillating at, and then converts these into pitch and volume data to be fed to the SID audio chip.

[Linus Åkesson] demonstrates the build ably by performing a slow rendition of Amazing Grace. The SID synthesizer chip in the C64 does a passable job emulating a theremin, used here with a modulated pulse wave sound. It’s an impressive build and one we fully expect to see at a big chiptune show sooner rather than later. We’re almost surprised nobody came out with a C64 Theremin cartridge back in the day.

We’ve seen other fancy theremin-inspired builds recently too, like this light-based design.

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A Commodore 64 running a smartwatch link program

The Commodore 64 Smartwatch Can Now Sync With Your Commodore 64 Desktop

July 18, 2022 by Robin Kearey 5 Comments

If you’ve got a smartwatch on your wrist, chances are you’ve also got a device nearby that links up with it. Most modern watches will happily sync with Android devices or iPhones, and some will also talk to Windows PCs. But what if you’re running an alternative OS? Something like, say, Commodore BASIC? In that case, you might want to check out [Nick Bild]’s latest project, which lets you to sync your smartwatch to your Commodore 64.

Sadly, you can’t just use any old smartwatch: the project is an extension of [Nick]’s Commodore 64 Smartwatch that we featured earlier. This watch can run Commodore 64 programs thanks to a custom software stack, but like most typical smartwatches also includes an accelerometer that counts your steps. Syncing the step counter to your computer is straightforward: after you come home from your daily run, you simply tap “sync” on the watch, enter LOAD"SYNC.PRG",8,1 on your Commodore 64, and the computer will show your total step count.

The C64 watch communicates with the host computer through a built-in infrared port. The classic Commodore computers don’t have an IR receiver, so [Nick] built one himself using an Arduino Micro hooked up to the C64’s User port. A custom program reads out the data and shows the step count on the screen.

Although the feature set of this app is a bit limited, [Nick]’s project demonstrates how the good old Commodore 64 can still perform useful tasks in today’s world. Not that we needed much reminding: after all, we’ve even seen it run AI applications using TensorFlow Lite.

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TensorFlow Lite – On A Commodore 64

July 6, 2022 by Jenny List 4 Comments

TensorFlow is a machine learning and AI library that has enabled so much and brought AI within the reach of most developers. But it’s fair to say that it’s not for the less powerful computers. For them there’s TensorFlow Lite, in which a model is created on a larger machine and exported to a microcontroller or similarly resource-constrained one. [Nick Bild] has probably taken this to its extreme though, by achieving this feat on a Commodore 64. Not just that, but he’s also done it using Commodore BASIC.

TensorFlow Lite works by the model being created as a C array which is then parsed and run by an interpreter on the microcontroller. This is a little beyond the capabilities of the mighty 64, so he has instead created a Python script that does the job of the interpreter and produces Commodore BASIC code that can run on the 64. The trusty Commodore was one of the more powerful home computers of its day, but we’re fairly certain that its designers never in their wildest dreams expected it to be capable of this!

If you’re interested to know more about TensorFlow Lite, we’ve covered it in the past.

Header: MOS6502, CC BY-SA 3.0.

Will The Real Commodore Please Stand Up?

June 16, 2022 by Jenny List 28 Comments

The Commodore 64 is a much-loved 8-bit retro computer that first appeared in 1982 and finally faded away around a decade later. The Commodore company started by [Jack Tramiel] went on to make the Amiga, and eventually ceased trading some time in the late 1990s. All history, now kept alive only by enthusiasts, right? Well, not quite, as the C64 has been the subject of a number of revivals both miniature and full-sized over the years. The latest came in the form of a Kickstarter for the C64x, a seemingly legitimately-branded Commodore 64-shaped PC, but it seems that has now been paused due to a complaint from an Italian company claiming to be the real heirs of Commodore. So will the real Commodore please stand up?

The origin of the Kickstarter C64x breadbin C64 PC is well enough documented, having its roots in a legitimate 2010 offering for which the person behind the C64x appears to have gained the rights. The Italian company is also called Commodore and uses the familiar branding from the glory days to sell some Commodore-themed games, novelties, and a tablet computer, but its website is a little tight-lipped about how it came by the use of that IP. Could it have come upon those rights through the 1990s German owner of the brand, Escom? We’d be fascinated to know.

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A (Nearly All) New Commodore 64

May 4, 2022 by Jenny List 10 Comments

The Commodore 64 remains one of the most influential of the 8-bit home computers four decades after its launch, so not surprisingly there is a huge enthusiast community surrounding it. With so many produced over the years it was available one might think that there would be no shortage of surviving specimens, but sadly time and component failure have taken their toll and the classic micro is not always the most reliable kid on the block. Thus a cottage industry has sprung up supplying C64 parts, leading [The Retro Shack] to have a go at making a new one entirely from scratch.

As you can see in the video below the break it’s not quite an entirely new ’64, as parts including some of the custom silicon come from failed boards. The PCB is a modern recreation of the original and the SID sound chip is an ARMsid though, and most of the parts come from a handy bagged-up kit that makes assembling the BoM much easier. Instead of the big silver box of the original RF modulator is a modern composite board, and there are a few issues with minor connector part differences.

Assembly is simply a very long through-hole soldering process, and once he’d completed it there was the expected refusal to work. We’ve all been there, and eventually he traced it to an incorrectly fitted chip. If you think you’ve seen a few brand new C64s here before you’d be correct, one of them even used LEGO for those elusive keycaps.

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