Retrocomputing

1467 Articles

The Sixteen-Year Odyssey To Finally Emulate The Pioneer LaserActive Console

September 8, 2025 by 16 Comments

The 1993 Pioneer LaserActive certainly ranks high on the list of obscure video games. It was an odd duck; it used both a LaserDisc for data storage and provided compatibility with a range of existing video game consoles. Due to the rarity and complexity of this system, emulating it has proven to be a challenge. The Ares emulator version 146 is the first to officially add support for the LaserActive. You’d expect getting to that point to be a wild journey. It was, and [Read Only Memo] documented the author’s ([Nemesis]) quest to emulate the odd little machine.

The LaserActive had a brief lifespan, being discontinued in 1996 after about 10,000 units sold. Its gimmick was that in addition to playing regular LaserDiscs and CDs, it could also use expansion modules (called PACs) to support games for other consoles, including the Sega Genesis and the NEC TurboGrafx-16. You could also get PACs for karaoke or to connect to a computer.

By itself, that doesn’t seem too complex, but its LaserDisc-ROM (LD-ROM) format was tough. The Mega LD variation also presented a challenge. The LD-ROMs stored entire games (up to 540 MB) that were unique to the LaserActive. Finding a way to reliably dump the data stored on these LD-ROMs was a major issue. Not to mention figuring out how the PAC communicates with the rest of the LaserActive system. Then there’s the unique port of Myst to the LaserActive, which isn’t a digital game so much as an interactive analog video experience, which made capturing it a complete nightmare.

With that complete, another part of gaming history has finally been preserved and kept playable. Sure, we have plenty of Game Boy emulators. Even tiny computers now are powerful enough to do a good job emulating the systems of yesterday.

A photo of two magnetic bubble memories installed in a circuit board

Scott Baker’s Magnetic Bubble Memory Mega-Post

September 5, 2025 by 11 Comments

Over on his blog our hacker [Scott Baker] has a Magnetic Bubble Memory Mega-Post.

If you haven’t heard of magnetic bubble memory before it’s basically obsolete nonvolatile memory. Since the 1970s when it was introduced this type of memory has been outperformed in every dimension including durability, reliability, price, density, performance, and so on. For any given application of bubble memory you will be able to find an alternative technology which is better in many ways. Except if you want some old tech to geek out over, in that case magnetic bubble memory is for you!

Continue reading “Scott Baker’s Magnetic Bubble Memory Mega-Post” →

Microsoft BASIC For 6502 Is Now Open Source

September 4, 2025 by 29 Comments

An overriding memory for those who used 8-bit machines back in the day was of using BASIC to program them. Without a disk-based operating system as we would know it today, these systems invariably booted into a BASIC interpreter. In the 1970s the foremost supplier of BASIC interpreters was Microsoft, whose BASIC could be found in Commodore and Apple products among many others. Now we can all legally join in the fun, because the software giant has made version 1.1 of Microsoft BASIC for the 6502 open source under an MIT licence.

This version comes from mid-1978, and supports the Commodore PET as well as the KIM-1 and early Apple models. It won’t be the same as the extended versions found in later home computers such as the Commodore 64, but it still provides plenty of opportunities for retrocomputer enthusiasts to experiment. It’s also not entirely new to the community, because it’s a version that has been doing the rounds unofficially for a long time, but now with any licensing worries cleared up. A neat touch can be found in the GitHub repository, with the dates on the files being 48 years ago.

We look forward to seeing what the community does with this new opportunity, and given that the 50-year-old 6502 is very much still with us we expect some real-hardware projects. Meanwhile this isn’t the first time Microsoft has surprised us with an old product.

Header image: Michael Holley, Public domain.

Scott and his Prompt 80

Restoring A Vintage Intel Prompt 80 8080 Microcomputer Trainer

September 3, 2025 by 3 Comments

Over on his blog our hacker [Scott Baker] restores a Prompt 80, which was a development system for the 8-bit Intel 8080 CPU.

[Scott] acquired this broken trainer on eBay and then set about restoring it. The trainer provides I/O for programming, probing, and debugging an attached CPU. The first problem discovered when opening the case is that the CPU board is missing. The original board was an 80/10 but [Scott] ended up installing a newer 80/10A board he scored for fifty bucks. Later he upgraded to an 80/10B which increased the RAM and added a multimodule slot.

[Scott] has some luck fixing the failed power supply by recapping some of the smaller electrolytic capacitors which were showing high ESR. Once he had the board installed and the power supply functional he was able to input his first assembly program: a Cylon LED program! Making artistic use of the LEDs attached to the parallel port. You can see the results in the video embedded below.

Continue reading “Restoring A Vintage Intel Prompt 80 8080 Microcomputer Trainer” →

CP/M Gently

September 3, 2025 by 13 Comments

If you are interested in retrocomputers, you might be like us and old enough to remember the old systems and still have some of the books. But what if you aren’t? No one is born knowing how to copy a file with PIP, for example, so [Kraileth] has the answer: A Gentle Introduction to CP/M.

Of course, by modern standards, CP/M isn’t very hard. You had disks and they had a single level of files in them. No subdirectories. We did eventually get user areas, and the post covers that near the end. It was a common mod to treat user 0 as a global user, but by default, no.

Continue reading “CP/M Gently” →

A hand holding a One ROM with a Commodore 64 in the background

One ROM: The Latest Incarnation Of The Software Defined ROM

September 3, 2025 by 25 Comments

Retrocomputers need ROMs, but they’re just so read only. Enter the latest incarnation of [Piers]’s One ROM to rule them all, now built with a RP2350, because the newest version is 5V capable. This can replace the failing ROMs in your old Commodore gear with this sweet design on a two-layer PCB, using a cheap microcontroller.

[Piers] wanted to use the RP2350 from the beginning but there simply wasn’t space on the board for the 23 level shifters which would have been required. But now that the A4 stepping adds 5 V tolerance [Piers] has been able to reformulate his design.

The C64 in the demo has three different ROMs: the basic ROM, kernel ROM, and character ROM. A single One ROM can emulate all three. The firmware is performance critical, it needs to convert requests on the address pins to results on the data bus just as fast as it can and [Piers] employs a number of tricks to meet these requirements.

The PCB layout for the RP2350 required extensive changes from the larger STM32 in the previous version. Because the RP2350 uses large power and ground pads underneath the IC this area, which was originally used to drop vias to the other side of the board, was no longer available for signal routing. And of course [Piers] is constrained by the size of the board needing to fit in the original form factor used by the C64.

The One ROM code is available over on GitHub, and the accompanying video from [Piers] is an interesting look into the design process and how tradeoffs and compromises and hacks are made in order to meet functional requirements.

Continue reading “One ROM: The Latest Incarnation Of The Software Defined ROM” →

An Amiga Demo With No CPU Involved

September 2, 2025 by 27 Comments

Of the machines from the 16-bit era, the Commodore Amiga arguably has the most active community decades later, and it’s a space which still has the power to surprise. Today we have a story which perhaps pushes the hardware farther than ever before: a demo challenge for the Amiga custom chips only, no CPU involved.

The Amiga was for a time around the end of the 1980s the most exciting multimedia platform, not because of the 68000 CPU it shared with other platforms, but because of its set of custom co-processors that handled tasks such as graphics manipulation, audio, and memory. Each one is a very powerful piece of silicon capable of many functions, but traditionally it would have been given its tasks by the CPU. The competition aims to find how possible it is to run an Amiga demo entirely on these chips, by using the CPU only for a loader application, with the custom chip programming coming entirely from a pre-configured memory map which forms the demo.

The demoscene is a part of our community known for pushing hardware to its limits, and we look forward to seeing just what they do with this one. If you have never been to a demo party before, you should, after all everyone should go to a demo party!

Amiga CD32 motherboard: Evan-Amos, Public domain.