Retrocomputing

1403 Articles

That’s No Moon, Er, Selectric

August 12, 2025 by 5 Comments

If you learned to type anytime in the mid-part of the 20th century, you probably either had or wanted an IBM Selectric. These were workhorses and changed typing by moving from typebars to a replaceable element. They were expensive, though worth it since many of them still work (including mine). But few of us could afford the $1,000 or more that these machines cost back in the day, especially when you consider that $1,000 was enough to buy a nice car for most of that time. [Tech Tangents] looks at something different: a clone Selectric from the sewing machine and printer company Juki.

The typewriter was the brainchild of [Thomas O’Reilly]. He sold typewriters and knew that a $500 compatible machine would sell. He took the prototype to Juki, which was manufacturing typewriters for Olivetti at the time.

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Don’t Say This DIY Diskette Was A Flop

August 11, 2025 by 21 Comments

Sometimes, you build a thing because you need a thing. Sometimes, you do it just to see if you can. This project is in category two: [polymatt] didn’t need to create a floppy disk from scratch-– plenty of old disks still exist– but we’re glad he made the attempt because it makes for a fascinating video that’s embedded below.

Some of you are going to quibble with the terminology [polymatt] uses in this video: first of all, he didn’t begin by creating the universe, so is he really starting “from scratch”? Secondly, the “floppy” format he’s attempting to copy is a 3½” diskette, which does not flop at all.

Choosing newer stiff-walled medium does allow him to practice his CNC skills and make the coolest-looking floppy enclosure we’ve ever seen. (It turns out brushed aluminum is even cooler-looking than the translucent neon ones.) On the other hand, we can’t help but wonder if a lower-density format 5¼” disk might have been an easier hurdle to jump. The diskette that was built does magnetize, but it can’t read or write actual files. We wonder if the older format might have been more forgiving of grain size and composition of his ferrite coating. Even more forgiving still would be to use these techniques to make magnetic tape  which is a perfectly viable way to store data.

Instead of storing data, you could make your own cleaning floppy. It’s not like data storage was really the point here, anyway– its not the destination, but the journey. So whatever you call this DIY diskette, please don’t call it a flop.

Thanks to [Anonymous] for the great tip!

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Amiga Programming In 2025 With AmiBlitz

August 10, 2025 by 30 Comments

Having owned an Amiga microcomputer is apparently a little bit like having shaken hands with Shoggoth: no one can escape unchanged from the experience. Thirty-two years on, [Neil] at The Retro Collective remains haunted by the memories — specifically, the memory of BlitzBasic 2, an Amiga-specific programming language he never found the time to use. What better time to make a game for the Amiga than the year 2025 of the common era?

[Neil] takes us on a long journey, with more than a little reminiscing along the way. BlitzBasic may not have been the main programming language for the Amiga, but it was by no means the least, with a good pedigree that included the best-selling 1993 game Skidmarks. Obviously BlitzBasic was not a slow, interpreted language as one might think hearing “BASIC”. Not only is it a compiled language, it was fast enough to be billed as the next best thing to C for the Amiga, according to [Neil].

[Neil] wasn’t the only one whose dreams have been haunted by the rugose touch of the Amiga and its scquomose BlitzBasic language– you’ll find a version on GitHub called AmiBlitz3 that is maintained by [Sven] aka [honitas] to this day, complete with an improved IDE. The video includes a history lesson on the open-source AmiBlitz, and enough information to get you started.

For the vibe-coders amongst you, [Neil] has an excellent tip that you can use LLMs like ChatGPT to help you learn niche languages like this not by asking for code (which isn’t likely to give you anything useful, unless you’ve given it special training) but by requesting techniques and psudocode you can then implement to make your game. The LLM also proved a useful assistent for [Neil]’s excel-based pixel art workflow.

If you’re wondering why bother, well, why not? As [Neil] says, writing Amiga games is his version of a crossword puzzle. It may also be the only way to keep the dreams at bay. Others have taken to writing new operating systems  or reproducing PCBs to keep vintage Amiga hardware alive. If some gather under the light of the full moon to chant “Ia! Ia! Commodore f’thagan”– well, perhaps we can thank them for Commodore for rising from the sunless depths of bankruptcy once again.

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SparcStation 1+ Finally Gets Attention

August 9, 2025 by 12 Comments

We can’t throw stones. [Leaded Solder] picked up a SparcStation 1+ in 2018 and found it only produced illegal instruction errors. We’re sure he’s like us and meant to get back to it, and, instead, it sat on the bench, taking up space. You eventually have to move it, though, so seven years later, it was time for another go at it.

The first pass back in 2018 revealed that the machine had an interesting life. The full-sized hard drive was salvaged from an Apple computer. Removing the drive resolved the illegal instruction error. The drive seemed to work, but there was still nothing that suggested the machine would fully boot up. The next step was to try booting from a floppy, but that didn’t work either. The floppy cable had been surgically altered, again hinting this machine had seen some tough love.

Fast forward to 2025. This time, a Pi Pico-based SCSI emulator would stand in for the aging and suspect hard drive. Unfortunately, as noted, this machine has undergone some extensive and strange surgery. The power cable feeding the emulator had been rewired backwards, exposing the poor Pi Pico to 12 V, with predictable results. Luckily, it didn’t seem to phase the SparcStation.

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2025 One Hertz Challenge: The Real-Time Clock The VIC-20 Never Had

August 8, 2025 by 6 Comments

Like many early microcomputers, the Commodore VIC-20 did not come with an interna real-time clock built into the system. [David Hunter] has seen fit to rectify that with an add-on module as his entry to the 2025 One Hertz Challenge.

[David]’s project was inspired by a product that Hayes produced in the 1980s, which provided a serial-port based real-time clock solution for computers that lacked one on board. The heart of the project is an Arduino Uno, which itself uses a Dallas DS3231 RTC module to keep accurate time. [David] then drew from an IEC driver developed by [Lars Pontoppidan] for the MM2IEC project. This enables the Arduino to report the time to the VIC-20 via its IEC port.

The project is a neat way to provide a real-time clock source to programs written in Commodore BASIC. It’s also perfectly compatible with the IEC bus, so it can be daisy chained along with printers and disk drives without issue. [David] hasn’t tested it with a Commodore 64, but he suspects it should work just as well on that platform, too.

If you’ve ever wanted to build something clock-based for the VIC-20 but didn’t know how, this is a great piece of hardware to solve that problem. Meanwhile, you might find joy in reading about real-time clock hacks for other systems like the Raspberry Pi. Meanwhile, if you’re working on your own nifty timekeeping projects, don’t hesitate to let us know!

2025 Hackaday One Hertz Challenge

Exploring The TRS-80’s Color BASIC’s Random Number Function

August 8, 2025 by 6 Comments

Although these days we get to tap into many sources of entropy to give a pretty good illusion of randomness, home computers back in the 1980s weren’t so lucky. Despite this, their random number generators were good enough for games and such, as demonstrated by the [CoCo Town] YouTube channel.

The CoCo is the nickname for the TRS-80 Color Computer, which despite its name, shares absolutely nothing with the TRS-80. Its BASIC version is called Color BASIC, which like many others was based on Microsoft BASIC, so the video’s description should be valid for many other BASIC versions as well. In the video we’re first taken through a basic summary of what the floating point format is all about, before running through an example of the algorithm used by Color BASIC for its RND function, using a test program written in Color BASIC.

As described in the video, the used algorithm appears to be the linear congruential generator, which is a pseudo-random generator that requires minimal resources from the hardware it runs on. Of course, its main disadvantage is that it will fairly rapidly begin to repeat itself, especially with a limited number of output bits. This makes it a decent choice even today for something like simple game logic where you just want to get some variation without aiming for cryptographically secure levels of randomness.

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Happy Birthday 6502

August 4, 2025 by 121 Comments

The MOS Technology 6502 is a microprocessor which casts a long shadow over the world of computing. Many of you will know it as the beating heart of so many famous 8-bit machines from the likes of Commodore, Apple, Acorn, and more, and it has retained enough success for a version to remain in production today. It’s still a surprise though, to note that this part is now fifty years old. Though there are several contenders for its birthday, the first adverts for it were in print by July 1975, and the first customers bought their chips in September of that year. It’s thus only fitting that in August 2025, we give this processor a retrospective.

The Moment Motorola Never Really Recovered From

A double page advert for the MOS 6501 and 6502, advertising its low cost and high performance.
The advert that started it all. MOS Technology, Public domain.

The story of the 6502’s conception is a fascinating tale of how the giants of the early mocroprocessor industry set about grappling with these new machines. In the earlier half of the 1970s, Chuck Peddle worked for Motorola, whose 6800 microprocessor reached the market in 1974. The 6800 was for its time complex, expensive, and difficult to manufacture, and Peddle’s response to this was a far simpler device with a slimmed-down instruction set that his contact with customers had convinced him the market was looking for: the 6502.

There’s a tale of Motorola officially ordering him to stop working on this idea, something he would later assert as such an abandonment of the technology that he could claim the IP for himself. Accompanied by a group of his Motorola 6800 colleagues, in the summer of 1974 he jumped ship for MOS Technology to pursue the design. What first emerged was the 6501, a chip pin-compatible with the 6800, followed soon after by the 6502, with the same core, but with an on-board clock oscillator. Continue reading “Happy Birthday 6502” →