commodore 64

117 Articles

Linus Live-Codes Music On The Commodore 64

October 16, 2024 by 12 Comments

In this tremendously educational video, [Linus Åkesson] takes us through how he develops a synthesizer and a sequencer and editor for it on the Commodore 64, all in BASIC. While this sounds easy, [Linus] is doing this in hard mode: all of the audio is generated by POKE, and it gets crazier from there. If you’re one of those people out there who think that BASIC is a limited language, you need to watch this video.

[Linus] can do anything with POKE. On a simple computer like the C64, the sound chip, the screen chips, and even the interrupts that control program flow are all accessible simply by writing to the right part of memory. So the main loop here simply runs through a lot of data, POKEing it into memory and turning the sound chip on and off. There’s also a counter running inside the C64 that he uses to point into a pitch lookup table in the code.

But the inception part comes when he designs the sequencer and editor. Because C64 BASIC already has an interactive code editor, he hijacks this for his music editor. The final sequencer interface exists inside the program itself, and he writes music in the code, in real time, using things like LIST and editing. (Code is data, and data is code.) Add in a noise drum hack, and you’ve got some classic chiptuney sounds by the end.

We love [Linus]’s minimal C64 exercises, and this one gets maximal effect out of a running C64 BASIC environment. But that’s so much code in comparison to his 256-byte “A Mind is Born” demo. But to get that done, he had to use assembly.

Thanks [zogzog] for the great tip!

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C64 Gets A Graphics Upgrade Courtesy Of Your Favorite Piano Manufacturer

October 11, 2024 by 37 Comments

The Commodore 64 was quite a machine in its time, though a modern assessment would say that it’s severely lacking in the graphical department. [Vossi] has whipped up a bit of an upgrade for the C64 and C128, in the form of a graphics expansion card running Yamaha hardware.

As you might expect, the expansion is designed to fit neatly into a C64 cartridge slot. The card runs the Yamaha V9958—the video display processor known for its appearance in the MSX2+ computers. In this case, it’s paired with a healthy 128 kB of video RAM so it can really do its thing. The V9958 has an analog RGB output that can be set for PAL or NTSC operation, and can perform at resolutions up to 512×212 or even 512×424 interlaced. Naturally, it needs to be hooked directly up to a compatible screen, like a 1084, or one with SCART input. [Vossi] took the time to create some demos of the chip’s capabilities, drawing various graphics in a way that the C64 couldn’t readily achieve on its own.

It’s a build that almost feels like its from an alternate universe, where Yamaha decided to whip up a third-party graphics upgrade for the C64. That didn’t happen, but stranger team ups have occurred over the years.

[Thanks to Stephen Walters for the tip!]

New Release Of Vision Basic: Hot New Features!

September 23, 2024 by 7 Comments

As the Commodore 64 ages, it seems to be taking on a second life. Case in point: Vision BASIC is a customized, special version of the BASIC programming language with a ton of features to enable Commodore 64 programs to be written more easily and with all sorts of optimizations. We’ve tested out both the original 1.0 version of Vision BASIC, and now with version 1.1 being released there are a whole host of tweaks and updates to make the experience even better!

One of the only limitation of Vision BASIC is the requirement for expanded RAM. It will not run on an unexpanded C64 — but the compiled programs will, so you can easily distribute software made using Vision on any C64. A feature introduced in version 1.1 is support for GeoRAM, a different RAM expansion cartridge, and modern versions of GeoRAM like the NeoRAM which has battery-backed RAM. This allows almost instantaneous booting into the Vision BASIC development environment.

Some of the standout features include a doubling of compilation speed, which is huge for large programs that take up many REU segments in source form. There are new commands, including ALLMOBS for setting up all sprites with a single command; POLL to set up which joystick port is in use; CATCH to wait for a particular scanline; and plenty more! Many existing commands have been improved as well. As in the original version of Vision BASIC, you can freely mix 6510 assembly and BASIC wherever you want. You can use the built-in commands for bitmaps, including panning, collision detection, etc., or you can handle it in assembly if you want! And of course, it comes with a full manual — yes, a real, printed book!

One of the nice features of Vision BASIC is the customization of the development environment. On the first run, after agreeing to the software terms, you enter your name and it gets saved to the Vision BASIC disk. Then, every time you start the software up, it greets you by name! You can also set up a custom colour scheme, which also gets saved. It’s a very pleasant environment to work in. Depending on how much additional RAM you have, you can hold multiple program segments in different RAM banks. For example, you could have all your source code in one bank, all your bitmaps and sprites in another, and your SID tunes in yet another. The compiler handles all this for you when you go to compile the program to disk, so it’s easy to keep large programs organized and easy to follow.

If you’ve always wanted to write a game or application for the C64 but just didn’t know how to get started, or you felt daunted at having to learn assembly to do sprites and music, Vision BASIC is a great option. You will be blown away at the number of commands available, and as you become more experienced you can start to sprinkle in assembly to optimize certain parts of your code if desired.

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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You Can Program AVRs From The Commodore 64

July 26, 2024 by 10 Comments

These days, most of our microcontroller boards come with bootloaders so you can squirt hex into them straight over USB. However, you don’t need to do things this way. If you’re more old school, you can program your AVRs right from a Commodore 64. [Linus Akesson] shows us how.

Programming an AVR isn’t that hard. By holding the chip in reset, it’s possible to flash code via a serial protocol using just three wires. However, that’s pretty impractical to do with modern PCs — they don’t come with addressable IO pins anymore. Normally, you’d use a dedicated programmer to do the job, but [Linus] found his had died on a Friday night. So he set about turning his C64 into one instead.

He decided to use the pins of the C64’s Joystick Port 2, with pins 1, 2, 3, and 4 hooked up to SCK, MOSI, Reset, and MISO on the AVR, respectively. 5 V and Ground were also provided courtesy of the C64’s port. He then whipped up a simple bit of assembly code to read a bit of AVR hex and spit it out over the Joystick port following the in-circuit programming protocol. With a 1541 Ultimate to load files on to the C64 in hand, it was easy to pull his compiled AVR program off his modern PC, chuck it on the C64, and then get the old Commodore to program the AVR in turn.

It’s not the first time [Linus] has wowed us with a C64 in hand. If you’ve got your own fresh projects for the best-selling computer of all time, don’t hesitate to let us know!

A C64 SID Replacement With Built-in Games

June 11, 2024 by 9 Comments

Developer [frntc] has recently come up with a smaller and less expensive way to not only replace the SID chip in your Commodore 64 but to also make it a stereo SID! To top it off, it can also hold up to 16 games and launch them from a custom menu. The SIDKick Pico is a simple board with a Raspberry Pi Pico mounted on top. It uses a SID emulation engine based on reSID to emulate both major versions of the SID chip — both the 6581 and the 8580. Unlike many other SID replacements, the SIDKick Pico also supports mouse and paddle inputs, meaning it replaces all functionality of the original SID!

Sound can be generated in three different ways: either using PWM to create a mono audio signal that is routed out via the normal C64/C128 connectors, an external PCM5102A DAC board, or using a different PCB design that has pads for an on-board DAC and TL072 op-amp. While many Commodore purists dislike using replacement chips, the reality is that all extant SID chips were made roughly 40 years ago, and as more and more of them fail, options like the SIDKick Pico are an excellent way to keep the sound of the SID alive.

If you want to hear the SIDKick Pico in action, you can check out the samples on the linked GitHub page, or check out the video below by YouTuber Wolfgang Kierdorf of the RETRO is the New Black channel. To get your hands on a SIDKick Pico, you can follow the instructions on the GitHub page for ordering either bare PCBs or pre-assembled PCBs from either PCBWay or your board manufacturer of choice.

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Generative AI Hits The Commodore 64

May 15, 2024 by 5 Comments

Image-generating AIs are typically trained on huge arrays of GPUs and require great wads of processing power to run. Meanwhile, [Nick Bild] has managed to get something similar running on a Commodore 64. (via Tom’s Hardware).

A figure generated by [Nick]’s C64. We shall name him… “Sword Guy”!
As you might imagine, [Nick’s] AI image generator isn’t churning out 4K cyberpunk stills dripping in neon. Instead, he aimed at a smaller target, more befitting the Commodore 64 itself. His image generator creates 8×8 game sprites instead.

[Nick’s] model was trained on 100 retro-inspired sprites that he created himself. He did the training phase on a modern computer, so that the Commodore 64 didn’t have to sweat this difficult task on its feeble 6502 CPU. However, it’s more than capable of generating sprites using the model, thanks to some BASIC code that runs off of the training data. Right now, it takes the C64 about 20 minutes to run through 94 iterations to generate a decent sprite.

8×8 sprites are generally simple enough that you don’t need to be an artist to create them. Nonetheless, [Nick] has shown that modern machine learning techniques can be run on slow archaic hardware, even if there is limited utility in doing so. Video after the break.

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