retrocomputing

338 Articles

KiCad render of µLind pcb

The 6809 8-Bit Microcomputer: A Father-Son Odyssey

December 6, 2024 by 22 Comments

If you’re nostalgic for the golden age of microprocessors and dream of building your own computer, this story might spark your imagination. [Eric Lind], passionate retro enthusiast and his 14-year-old son, embarked on a mission to craft a microcomputer from scratch, centred around the exotic Motorola 6809 chip: the µLind.

What sets this project apart is its ambition: bridging retro computing with modern enhancements. Starting with just a 6809 and some basic peripherals, the men designed a multi-stage roadmap to realize their dream. Each stage brought new challenges: debugging an address decoder, reworking memory management, and evolving glue logic into programmable GAL chips. Fascinatingly, the project isn’t just about nostalgia—it’s a playground for exploring multitasking operating systems and pushing the boundaries of 8-bit computing.

Their creativity shines in solutions like a C64-compatible joystick port, add-on expansion cards, and a memory overkill of 1MB RAM. With every setback—a missing pull-up resistor or a misrouted IRQ signal—their determination grew stronger. By combining old-school know-how with modern tools like KiCad, they’ve created something that is both personal and profoundly inspiring.

[Eric]’s hope and goal is to establish a community of people that want to expand beyond the traditional Z80 and 6502 based SBC’s. Interested? Read [Eric]’s project log on Hackaday.io and start crafting!

8-Bit Computers Crunch Advanced Scientific Computations

December 1, 2024 by 37 Comments

Although largely relegated to retrocomputing enthusiasts and embedded systems or microcontrollers now, there was a time when there were no other computers available other than those with 8-bit processors. The late 70s and early 80s would have seen computers with processors like the Motorola 6800 or Intel 8080 as the top-of-the-line equipment and, while underpowered by modern standards, these machines can do quite a bit of useful work even today. Mathematician [Jean Michel Sellier] wanted to demonstrate this so he set up a Commodore 64 to study some concepts like simulating a quantum computer.

The computer programs he’s written to do this work are in BASIC, a common high-level language of the era designed for ease of use. To simulate the quantum computer he sets up a matrix-vector multiplication but simplifies it using conditional logic. Everything is shown using the LIST command so those with access to older hardware like this can follow along. From there this quantum computer even goes as far as demonstrating a quantum full adder.

There are a number of other videos on other topics available as well. For example, there’s an AmigaBasic program that simulates quantum wave packets and a QBasic program that helps visualize the statistical likelihood of finding an electron at various locations around a hydrogen nucleus. While not likely to displace any supercomputing platforms anytime soon, it’s a good look at how you don’t need a lot of computing power in all situations. And, if you need a refresher on some of these concepts, there’s an overview on how modern quantum computers work here.

Ruined 1993 ThinkPad Tablet Brought Back From The Brink

November 18, 2024 by 10 Comments

Collecting retrocomputers is fun, especially when you find fully-functional examples that you can plug in, switch on, and start playing with. Meanwhile, others prefer to find the damaged examples and nurse them back to health. [polymatt] can count himself in that category, as evidenced by his heroic rescue of an 1993 IBM ThinkPad Tablet.

The tablet came to [polymatt] in truly awful condition. Having been dropped at least once, the LCD screen was cracked, the case battered, and all the plastics were very much the worse for wear. Many of us would consider it too far gone, especially considering that replacement parts for such an item are virtually unobtainable. And yet, [polymatt] took on the challenge nonetheless.

Despite its condition, there were some signs of life in the machine. The pen-based touch display seemed to respond to the pen itself, and the backlight sort of worked, too. Still, with the LCD so badly damaged, it had to be replaced. Boggling the mind, [polymatt] was actually able to find a 9.4″ dual-scan monochrome LCD that was close enough to sort-of fit, size-wise. To make it work, though, it needed a completely custom mount to fit with the original case and electromagnetic digitizes sheet. From there, there was plenty more to do—recapping, recabling, fixing the batteries, and repairing the enclosure including a fresh set of nice decals.

The fact is, 1993 IBM ThinkPad Tablets just don’t come along every day. These rare specimens are absolutely worth this sort of heroic restoration effort if you do happen to score one on the retro market. Video after the break.

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Atari’s Pac-Man Flop: How A Classic Went Off-Course

October 25, 2024 by 35 Comments

For fans of retro games, Pac-Man is nothing short of iconic—a game so loved it’s been ported to nearly every console imaginable. But the Atari 2600 version, released in 1982, left players scratching their heads – as laid out in a video by [Almost Something]. Atari had licensed Pac-Man to ride the wave of its arcade success, but the home version, programmed solely by [Todd Fry], missed the mark, turning an arcade icon into a surprising lesson in over-ambitious marketing.

Despite the hype, [Fry] faced an almost impossible task: translating Pac-Man’s detailed graphics and complex gameplay to the Atari’s limited 4 K cartridge with only 128 bytes of RAM. Atari’s strict limitations on black backgrounds and its choice to cut costs by sticking with a 4 K cartridge left the game barely recognizable. The famous pellet-chomping maze became simpler, colors were changed, and the iconic ghosts—reduced to single colors—flickered constantly. And then, Atari went all in, producing twelve million copies, betting on the success of universal appeal. In a twist, Pac-Man did sell in record numbers (over seven million copies) but still fell short of Atari’s expectations, leaving millions of unsold cartridges eventually dumped in a New Mexico landfill.

This debacle even kind of marked Atari’s 1983 decline. Still, Pac-Man survived the hiccup, evolving and outlasting its flawed adaptation on the 2600. If you’re interested in learning more about the ins and outs of game ports, check out the fantastic talk [Bob Hickman] gave during Supercon 2023.

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Building A ZX Spectrum Using Only New Parts

October 17, 2024 by 29 Comments

Ah, the Sinclair ZX Spectrum. A popular computer in Britain and beyond, but now rather thin on the ground. If you can’t find one, fear not, for now—you can apparently build a new one with new parts! [TME Retro] is here to demonstrate how.

Before you get excited, no—Sinclair has not risen from the dead. Instead, it’s simply down to the state of the retrocomputing community. There are enough reproduction parts and components out there for the ZX Spectrum that it’s now possible to assemble the whole computer from new bits. You can get new cases and new mechanical keyboards, and a 100% compatible motherboard in the form of the Harlequin board. The latter even reproduces the unobtainable Spectrum ULA glue logic chip in raw logic!

It’s neat to see the ZX Spectrum live on decades after the production lines ground to a halt. We’ve seen similar feats achieved with the legendary Commodore 64; you’d think we had enough of them given they were the best-selling computer of all time. Video after the break.

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Revisiting 1990’s Mac Games That Never Were

September 23, 2024 by 17 Comments

[John Calhoun] was digging around their old MAC hard drives, revisiting some abandoned shareware games they wrote over three decades ago, and has uploaded the recovered disk images to GitHub for everyone to take apart and play with. This repository has a few of the games complete with their development files and the compiler environment, a mixture of Think Pascal and C.

Back then, [John] had a solid mantra when creating projects, specifically prototyping fast and abandoning things quickly if they were not working out. The blog shows a list of twenty-eight projects, of which only five ever made it to release, with all the rest left to rot. This is reminiscent of the attitude around Silicon Valley of moving fast and breaking things. Anyway, reasons for ditching a project ranged from ‘too much sprite work’ for a D’n’D style game to simply ‘not fun’ for some with clunky control mechanisms. [John] even abandoned a neat-looking steampunk flight simulator due to the sheer amount of work needed. Of course, it’s not all lost effort. Much of the code written was reused across multiple projects; after all, there’s no point in re-writing a cosine lookup table if you’ve already got one kicking around in another project.

Still, it’s a fun trip down memory lane, looking deep into projects that never were and the development journey to becoming a successful programmer.

While it isn’t hard to find old Macintosh hardware, some are not in great shape. Here’s a fun Hackintosh project that uses retro parts. [John] was featured a while back, with his homage to his first mac, a sleek Rpi-powered eInk desk ornament. Finally, we can’t talk about recovering retro software without looking in detail at the floppy disk themselves.

Where Did The Japanese Computers Go?

September 22, 2024 by 23 Comments

If you are a retrocomputer person, at least in North America and Europe, you probably only have a hazy idea of what computers were in the Japanese market at the time we were all buying MSDOS-based computers. You may have heard of PC-98, but there were many Japanese-only computers out there, and a recent post by [Misty De Meo] asks the question: What happened to the Japanese computers?

To answer that question, you need a history lesson on PC-98 (NEC), FM Towns (Fujitsu), and the X68000 (Sharp). The PC-98 was originally a text-only MSDOS-based computer. But eventually, Microsoft and NEC ported Windows to the machine.

The FM Towns had its own GUI operating system. However, it too had a Windows port and the machine became just another Windows platform. The X68000, as you may well have guessed, used a 68000 CPU. Arguably, this was a great choice at the time. However, history shows that it didn’t work out, and when Sharp began making x86-based Windows machines — and, of course, they did — there was no migration path.

[Misty] makes an interesting point. While we often think of software like Microsoft Office as driving Windows adoption, that wasn’t the case in Japan. It turns out that multitasking was the key feature since Office, at the time, wasn’t very friendly to the native language.

So where did the Japanese computers go? The answer for two of them is: nowhere. They just morphed into commodity Windows computers. The 68000 was the exception — it just withered away.

Japanese pocket computers were common at one time and have an interesting backstory. Japanese can be a challenge for input but, of course, hackers are up to the challenge.