Retrocomputing

1267 Articles

Adding An Atari Joystick Port To TheC64 USB Joystick

April 24, 2025 by 1 Comment

“TheC64” is a popular recreation of the best selling computer of all time, the original Commodore 64. [10p6] enjoys hacking on this platform, and recently whipped up a new mod — adding a 9-pin Atari joystick connector for convenience.

When it comes to TheC64 units, they ship with joysticks that look retro, but aren’t. These joysticks actually communicate with the hardware over USB. [10p6]’s hack was to add an additional 9-pin Atari joystick connector into the joystick itself. It’s a popular mod amongst owners of TheC64 and the C64 Mini. All one needs to do is hook up a 9-pin connector to the right points on the joystick’s PCB. Then, it effectively acts as a pass-through adapter for hooking up other joysticks to the system.

While this hack could have been achieved by simply chopping away at the plastic housing of the original joystick, [10p6] went a tidier route. Instead, the joystick was granted a new 3D printed base that had a perfect mounting spot for the 9-pin connector. Clean!

We’ve seen some great hacks from [10p6] lately, like the neat reimagined “C64C” build that actually appears in this project video, too.

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C64 Assembly In Parts

April 23, 2025 by 18 Comments

[Michal Sapka] wanted to learn a new skill, so he decided on the Commodore 64 assembly language. We didn’t say he wanted to learn a new skill that might land him a job. But we get it and even applaud it. Especially since he’s written a multi-part post about what he’s doing and how you can do it, too. So far, there are four parts, and we’d bet there are more to come.

The series starts with the obligatory “hello world,” as well as some basic setup steps. By part 2, you are learning about registers and numbers. Part 3 covers some instructions, and by part 4, he finds that there are even more registers to contend with.

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A Scratch-Built Commodore 64, Turing Style

April 23, 2025 by 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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Trekulator: A Reproduction Of The 1977 Star Trek Themed Calculator

April 21, 2025 by 9 Comments

A recent project over on Hackaday.io from [Michael Gardi] is Trekulator – Where No Maker Has Gone Before.

This is a fun build and [Michael] has done a very good job of emulating the original device. [Michael] used the Hackaday.io logging feature to log his progress. Starting in September 2024 he modeled the case, got his original hardware working, got the 7-segment display working, added support for sound, got the keypad working and mounted it, added the TFT display and mounted it, wired up the breadboard implementation, designed and implemented the PCBs, added some finishing touches, installed improved keys, and added a power socket back in March.

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Remembering UCSD P-System, The Pascal Virtual Machine

April 21, 2025 by 22 Comments

Long before the Java Virtual Machine (JVM) was said to take the world by storm, the p-System  (pseudo-system, or virtual machine) developed at the University of California, San Diego (UCSD) provided a cross-platform environment for the UCSD’s Pascal dialect. Later on, additional languages would also be made available for the UCSD p-System, such as Fortran (by Apple Computer) and Ada (by TeleSoft), not unlike the various languages targeting the JVM today in addition to Java. The p-System could be run on an existing OS or as its own OS directly on the hardware. This was extremely attractive in the fragmented home computer market of the 1980s.

After the final release of version IV of UCSD p-System (IV.2.2 R1.1) in 1987, the software died a slow death, but this doesn’t mean it is forgotten. People like [Hans Otten] have documented the history and technical details of the UCSD p-System, and the UCSD Pascal dialect went on to inspire Borland Pascal.

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Restoration Of Six-Player Arcade Game From The Early 90s

April 21, 2025 by 9 Comments

Although the video game crash of the mid-80s caused a major decline in arcades from their peak popularity, the industry didn’t completely die off. In fact, there was a revival that lasted until the 90s with plenty of companies like Capcom, Midway, SEGA, and Konami all competing to get quarters, francs, loonies, yen, and other coins from around the world. During this time, Namco — another game company — built a colossal 28-player prototype shooter game. Eventually, they cut it down to a (still titanic) six-player game that was actually released to the world. [PhilWIP] and his associates are currently restoring one of the few remaining room-sized games that are still surviving.

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MilliForth-6502, A Forth For The 6502 CPU

April 20, 2025 by 34 Comments

Forth is popular on small computers because it is simple to implement, yet quite powerful. But what happens when you really need to shrink it? Well, if your target is the 6502, there’s milliForth-6502.

This is a port of milliForth, which is a fork of sectorforth. The sectorforth project set the standard, implementing a Forth so small it could fit in a 512-byte boot sector. The milliForth project took sectorforth and made it even smaller, weighing in at only 336 bytes. However, both milliForth and sectorforth are for the x86 architecture. With milliForth-6502, [Alvaro G. S. Barcellos] wanted to see how small he could make a 6502 implementation.

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