A Scratch-Built Commodore 64, Turing Style

April 23, 2025 by Dan Maloney 18 Comments

Building a Commodore 64 is among the easier projects for retrocomputing fans to tackle. That’s because the C64’s core chipset does most of the heavy lifting; source those and you’re probably 80% of the way there. But what if you can’t find those chips, or if you want more of a challenge than plugging and chugging? Are you out of luck?

Hardly. The video below from [DrMattRegan] is the first in a series on his scratch-built C64 that doesn’t use the core chipset, and it looks pretty promising. This video concentrates on building a replacement for the 6502 microprocessor — actually the 6510, but close enough — using just a couple of EPROMs, some SRAM chips, and a few standard logic chips to glue everything together. He uses the EPROMs as a “rulebook” that contains the code to emulate the 6502 — derived from his earlier Turing 6502 project — and the SRAM chips as a “notebook” for scratch memory and registers to make a Turing-complete random access machine.

[DrMatt] has made good progress so far, with the core 6502 CPU built on a PCB and able to run the Apple II version of Pac-Man as a benchmark. We’re looking forward to the rest of this series, but in the meantime, a look back at his VIC-less VIC-20 project might be informative.

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Converting The C64 Mini Into A C64C

April 14, 2025 by Lewin Day 14 Comments

The C64 Mini is a beautiful and functional replica of the most popular computer ever made, except at 50% size and without a working keyboard. For maximum nostalgia, it was modeled after the brown breadbox C64 case which so characterized the model. However, [10p6] wanted to build a tiny C64C instead, so set about making a conversion happen.

The build is primarily about the case design. [10p6] created a nice 50% scale duplicate of the C64C, with an eye to making it work with the internals of the popular C64 Mini. The case was paired with a custom PETSCII keyboard PCB and keycaps designed by [Bleugh]. This was a key element, since it wouldn’t really feel like a functional C64C without a functional keyboard. The build also scored a bonus USB hub for more flexibility. For the best possible finish, the case, power button, and keycaps were all printed using a resin printer, which provides a more “production-like” result than FDM printers are capable of.

It’s funny how retro computers remain popular to this day, particularly amongst the hacker set. In contrast, we don’t see a whole lot of people trying to replicate Pentium II machines from the mid-1990s. If you do happen to have a crack at it, though, the tipsline is always open. Video after the break.

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A Quarter And A Dime Will Get You A Commodore 64 Softmodem

January 20, 2025 by Lewin Day 43 Comments

Back in the 1980s, a viable modem cost hundreds of dollars. Even in the 1990s, you were looking at spending a a Benjamin or two to get computer squawking down the phone lines. According to [Cameron Kaiser], though, it’s possible to whip up a softmodem using a Commodore 64 for much cheaper than that. How much? Just 35 cents, we’re told!

The inspiration was simple—Rockwell apparently used to build modems using the 6502. The Commodore 64 has a 6502 inside, pretty much, so surely it could be a softmodem, right? Indeed, one [John Iannetta] had done this in a one-way form in the 1980s, using the Commodore 64’s SID audio chip to output data in sound form. In 1998, he espoused the 35-cent modem—basically, the price of buying an RCA jack to hook up a phone line to your Commodore 64.

As [Cameron] found out, the concept still works today, as does [John’s] code, but it’s more like 68 cents in 2025 dollars. With the right bits and pieces, and a little code, you can have your C64 modulating data into sound at rates of 300 baud.

It’s hacky, slow, and there’s no real way to receive—the C64 just doesn’t have the chops to demodulate these kinds of signals on its own. You also shouldn’t use it on a real phone line if you don’t want to damage your C64. Still, it’s a wonderful bit of hackery, and it’s fun to see how well it works. We’ve seen some other great Commodore 64 modem projects before, like the ever-useful RetroModem. Meanwhile, if you’ve got your own communication hacks for the computers of yesteryear, don’t hesitate to let us know!

C64 Gets A Graphics Upgrade Courtesy Of Your Favorite Piano Manufacturer

October 11, 2024 by Lewin Day 38 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 Alexander Rowsell 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.

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Exploring TapTo NFC Integration On The MiSTer

September 15, 2024 by Dave Rowntree 14 Comments

[Ken] from the YouTube channel What’s Ken Making is back with another MiSTer video detailing the TapTo project and its integration into MiSTer. MiSTer, as some may recall, is a set of FPGA images and a supporting ecosystem for the Terasic DE10-Nano FPGA board, which hosts the very capable Altera Cyclone V FPGA.

The concept behind TapTo is to use NFC cards, stickers, and other such objects to launch games and particular key sequences. This allows an NFC card to be programmed with the required FPGA core and game image. The TapTo service runs on the MiSTer, waiting for NFC events and launching the appropriate actions when it reads a card. [Ken] demonstrates many such usage scenarios, from launching games quickly and easily with a physical ‘game card’ to adding arcade credits and even activating cheat codes.

As [Ken] points out, this opens some exciting possibilities concerning physical interactivity and would be a real bonus for people less able-bodied to access these gaming systems. It was fun to see how the Nintendo Amiibo figures and some neat integration projects like the dummy floppy disk drive could be used.

TapTo is a software project primarily for the MiSTer system, but ports are underway for Windows, the MiSTex, and there’s a working Commodore 64 game loader using the TeensyROM, which supports TapTo. For more information, check out the TapTo project GitHub page.

We’ve covered the MiSTer a few times before, but boy, do we have a lot of NFC hacks. Here’s an NFC ring and a DIY NFC tag, just for starters.

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The Commodordion Gets A Big Usability Upgrade

August 28, 2024 by Lewin Day 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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