Retrocomputing

1643 Articles

PC-1: The 1954 Computer With No Tubes, Relays, Or Transistors

August 11, 2026 by 33 Comments

However you make a digital computer, you need something to represent a binary digit. Usually this is some form of switch: a relay, a tube, or a transistor, although there have been other ways to represent state. In 1954, [Eiichi Goto] of Japan invented the parametron, a resonant circuit using a ferrite core and a capacitor that could be moved between two phases.

According to [Goto’s] 1959 paper, the device is effectively a parametric oscillator, similar to some used at UHF frequencies by hams. The idea is that a tuned circuit is set to some frequency and driven with twice that frequency.

A What?

A parametron is essentially a resonant circuit made with inductors or capacitors whose reactance is varied at twice its resonant frequency. That “pumping” causes the circuit to oscillate at half the pump frequency. The neat trick is that there are two equally stable oscillation states at half the pump frequency, separated from each other by 180° of phase. Those two phases become binary 0 and 1. Depending on the incoming signals, one phase will win over the others.

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Whatever Happened To The Computer Of Tomorrow, Anyway? The Xerox Alto Story

August 9, 2026 by 42 Comments

You’ve almost certainly heard of the Xerox Alto, the machine that pioneered the desktop-mouse-keyboard interface and inspired Steve Jobs to produce the Apple Lisa and Macintosh computers. It wasn’t just having a desktop, though– so much of our modern computing paradigm was invented on these machines. Given that, why aren’t we all using Xerox clones instead of Apples or PCs descended from the IBM compatibles? [Ctrl+Alt+Fail] has a video that answers the question: whatever happened to the computer of tomorrow, anyway?

It goes through the whole story of the Alto, from its introduction at Xerox PARC in the 1970s to its demise. At the introduction, the engineers showed of the What You See Is What You Get word processor, networked the machines together to show off e-mail and that anyone could use the office laser printer. It all seems very familiar now, but at the time, it was a revolution. An expensive one. The monitor sitting on the desk wasn’t the computer, after all: that was a large filing-cabinet sized desk sitting underneath. Only about 2000 were ever built, so what happened?

It wasn’t just that the first units cost twelve grand USD to build in 1973 money– about 90 large today by CPI, or for the gold bugs that’s 96 oz or 2.7 kg. It wasn’t worth its weight in gold, but it was close. Still, that wasn’t the problem: later models would be cheaper. The problem was that Xerox refused to sell the thing in the 70s. They saw the potential of a paperless office, and it scared them. Sure, they could sell a computer, once. They wouldn’t get a monthly service fee, nor the cost of the toner, drums and other consumables the Alto wouldn’t need. So they sat on it, and let others like Steve Jobs who didn’t have an existing business empire to lose take their ideas and run with them.

It seems shortsighted, but Xerox had already lost millions on big iron computing around the same time the Alto came along, and every business decision after that was carefully weighed on its projected revenue. Compared to a copier that printed money for Xerox as surely as it printed paper, the Alto just didn’t look like it could pay for itself. It looked likely to lose them a lot of money, which, in fact the adoption of the personal computer ultimately did. Hindsight is 20/20 and it’s easy to play Monday Morning Quarterback and say these developments were inevitable and Xerox should have run out in front, but [Ctrl+Alt+Fail] does a good job of explaining the logic from the Xerox boards’ point of view, which makes the video very much worth a watch.

If you can’t get enough Alto, we can also point you to what it takes to restore one, what almost killed one, and why you shouldn’t mine bitcoin with one.

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The BBC Tetris Companion

August 7, 2026 by 2 Comments

[Leaded Solder] took on an interesting challenge. The BBC, apparently, produced a game console known as the BBC Bridge Companion that connected to your TV and helped you learn to play Bridge back in 1985. At £200, we doubt many were sold new, but there were nine ROM cartridges available, presumably at an additional cost. [Leaded Solder] doesn’t care about playing bridge, but decided to teach the computer itself to play Tetris.

Inside is what you might expect for 1985. A Z80 and TI video chip, although naturally enough, it is the PAL variant. With 16K of VRAM the machine would have been very capable for its day. Unlike some game systems, the Bridge Companion runs its own code before launching what’s on the ROM cartridge. That required a few evenings of reverse engineering to figure out the correct header. Meanwhile, the surplus real hardware needed a quick repair on its cartridge slot before he could test it with real metal.

There were more hurdles, including adapting the PAL output for a composite monitor. Don’t miss the second part of the series for more technical details, and we’ll be interested in following the posts to their conclusion later this month.

Oddly enough, we think this is the first time the BBC Bridge Companion has made an appearance on Hackaday. However, we’ve had no shortage of card shufflers.

Going Full Fruity With Apple’s 1999 High-End Power Mac G3

August 6, 2026 by 12 Comments

Back in the late 90s, Apple was definitely a pretty fruity company, with its aggressively translucent shades of colored plastic that often got described in terms of such fruit variants. Although the iMac steals a lot of the glory here, the Power Mac series and associated hardware deserves that spot in the limelight as well. Recently [Dan Wood] put together a full Power Mac G3-based setup, including the appropriate LCD monitor and other peripherals as someone with some serious disposable income back in 1999 might have owned.

Why Macs are better than PCs. (Credit: Dan Wood, YouTube)
Why Macs are better than PCs. (Credit: Dan Wood, YouTube)

Part of Steve Jobs’ return to Apple, the Power Macintosh G3 debuted first in basically recycled beige enclosures from previous Macintosh systems before its second generation introduced the Blue and White version, as it was officially called. This dazzling style was carried through in the peripherals, with pin stripes, translucent plastic and a distinct absence of sharp corners or edges.

As for what you get in these colorful Power Mac G3s, a 300 to 450 MHz CPU, an official memory limit of 192 MB and perhaps the most user-friendly way to access the logic board to upgrade and install components with the folding lid. Something which had PC users with sharp edged cases and plentiful blood sacrifices to the PC gods somewhat steaming in jealousy.

For the time these Power Mac G3s didn’t just look fetching, they also were quite powerful. Something which came at a pretty hefty price tag, of course. The 400 MHz model that [Dan] got his paws on would have cost around $2,000 back in 1999, or closer to $4,000 clams today. The active-matrix TFT LCD screen would have been cutting edge as well, with a similar cutting edge price tag.

Released before OS X this system runs Mac OS 8.6, though it can run OS X 10.4 (Tiger) which unlocks more software options and of course the transition to a proper multi-tasking OS. This particular system was apparently used for graphics design until 2010 based on the files on the HDD. As demonstrated in the video, the system is still quite usable, even in 2026, thanks to all the software available online.

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Amiga And Commodore, Back Together (Sort Of)

August 6, 2026 by 38 Comments

The story of Commodore, the famous manufacturer of home computers, is a murky one at best. Commodore fans will decry their woeful marketing and dismal product roadmap, while former employees such as our Hackaday colleague [Bil Herd] have shone a bit of light on the goings-on behind the scenes. The company’s final demise in the collapse of the German company Escom scattered its parts to the four winds, but now we find a potential return to clarity.

Amiga Corporation, holders of much of the Commodore and Amiga IP, have reached agreements with Commodore International Corporation, the recently formed face of the Commodore brand, and Hyperion Entertainment BV, who have been behind a series of Amiga developments over recent decades.

The press release provides a fascinating map of the Commodore and Amiga ecosystem as it stands in the 21st century, something which has sometimes eluded fans. As we understand it the rights to the 8-bit IP reside alongside the rights to the Amiga IP with Amiga Corporation, and it’s these 8-bit rights, or at least the software and documentation within them, that have been licensed to Commodore International Corporation. Meanwhile in a separate agreement the rights to continued development of AmigaOS 4.x remain with Hyperion, while the AmigaOS 3.x versions for the 68k Amigas will revert to Amiga Corporation at the end of 2027.

As far as we can see then, this should enable Commodore International Corporation to produce their line of 8-bit Commodore 64s and other machines, while Hyperion continue to serve the AmigaOS 4.x community. The interesting part comes in the AmigaOS 3.x versions, for which Amiga Corporation say they will continue to direct the development and evolution. Does that mean we’ll eventually see a 68k Amiga of some kind licensed through a company such as Commodore International Corporation? It’s an interesting prospect, and a story we’ll follow.

A Full Motion Video Codec For The Atari ST

August 4, 2026 by 6 Comments

Who says an old dog can’t do new tricks? The Atari ST has got to qualify as an “old dog” 41 years after launch, and if playing Full Motion Video (FMV) cutscenes– from DOS games of a decade later– doesn’t count as a new trick, we’re not sure what does. In this case, [Jonas Eschenburg] is the trainer and his fascinating write-up lets you know exactly how he did it.

Unlike the contemporary and pricier Amiga, Atari’s 68000-based home computer didn’t have any fancy graphics chips; everything has to go through the Motorolla CPU at a blistering 8MHz. Just porting classic DOS games like [Jonas Eschenburg] is doing with Command and Conquer— a title 10 years newer than the ST– is an amazing tour de force. Bringing the cutscenes along for the ride is just bonus, but what a bonus it is.

Granted, [Jonas] has to work within the Atari’s limitations, so it doesn’t quite look the same. The biggest limitation is of course the 16 colour planar graphics on the Atari, compared with 256 colours of chunky goodness that VGA offered. [Jonas] admits that getting good palettes to minimize artifacting is a challenge. Interestingly he’s not showing quite so many blocking artifacts we would expect from the technique he is using: to take advantage of how the ST’s memory is laid out, he’s using a codebook-based codec that splits the image into easily-addressable blocks. Both the palette and the codebook must update continuously as the film plays but that’s still easier on the antique hardware than streaming raw pixel data, which you cannot do. The whole article is absolutely worth a read, and the demo videos generously sprinkled through it are worth a look, too. We’ve included a demo of C&C‘s intro below. If you’re itching to play, the port is on Itch.io.

Speaking of DOS games, did you know the Atari ST can run doom? Multiple versions, even.

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At Last! CP/M For Protected Mode

August 4, 2026 by 34 Comments

If you used a serious computer pre-IBM PC, there was a fair chance its operating system was CP/M. CP/M was a staple among 8080 and Z80 computers and while there were other versions, we’ll always associate CP/M with the Z-80. There was a CP/M made for the PC which used an 8088 (a hybrid 8-bit bus with a 16-bit 8086 core), but it was overwhelmed by MSDOS. However, there was another interesting version made for the 68000, and now [johnsonjh] has ported that over to create an early version of CP/M for 80386 protected mode.

The Z-80 only had a 16-bit address bus, so it could only handle 64K of memory. It was common to “bank switch” some memory, and CP/M Plus could be made to understand that (for example, you might have 32K of common memory and three banks of 32K memory; you could address one bank at a time). However, the 386 had a full-blown memory management unit that could remap physical 4K memory pages to anywhere in a program’s virtual address space.

Ordinary CP/M couldn’t handle that, but the Motorola 68000 had a similar page management model, so it makes sense it might be easier to port CP/M-68K to the 80386 than starting from the original, even though the instruction set for the Z-80 is conceptually more similar to the 80386.

What can you do with it? We don’t know. Presumably, it will allow you to use lots of memory. Historically, CP/M software from one variant would not run on another, so you’ll have to build anything you want to use. Of course, the real killer for lots of CP/M memory was multitasking, but that takes MP/M, and only about half of that is currently working. But we won’t be surprised to see it completed soon.

While CP/M skills won’t land you many jobs these days, it is a pretty good way to get mentioned on Hackaday.