Animated gif of large 1950s computer spitting out a sheet of paper.

Retrotechtacular: 1960s Doc Calls Computers The Universal Machine

December 20, 2023 by Drew Littrell 5 Comments

It’s weird to think that an abacus would have still been used sixty years ago, or so posits the documentary series The Computer and the Mind of Man. This six part series originally aired on San Francisco local television station KQED in 1962, a time where few people outside of academia had even stood next to such a device.

Episode 3 titled “The Universal Machine” was dedicated to teaching the public how a computer can enhance every type of business provided humans can sufficiently describe it in coded logic. Though mainly filtered through IBM’s perspective as the company was responsible for funding the set of films; learning how experts of the time contextualized the computer’s potential was illuminating.

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The Sol-1: A 16-bit Computer In 74HC Logic With C Compiler And Unix-like OS

December 11, 2023 by Maya Posch 15 Comments

Sol-1 system pictured from the front. {Credit: Paulo Constantino)

While the concept of a computer system implemented in discrete logic ICs is by itself not among the most original ideas, the way some machines are executed certainly makes them stick out. This is the case with [Paulo Constantino]’s Sol-1, which not only looks extremely professional, but also comes with a lot of amenities that allow for system development, including a C compiler and assembler, a Unix-like OS (in development), DMA, and a whole host of interfaces to interact with the system and peripherals (serial, parallel, IDE, etc.). Not to mention a SystemVerilog model and an emulator, all of which can be found on [Paulo]’s GitHub.

More photos and videos can be found on [Paulo]’s YouTube channel, as well as the Sol-1 website, which shows off the intricate wire wrap work on the back of each PCB. In terms of the ISA, there are 5 general purpose registers (one scratch) which can also be used as two 8-bit registers each. Most operations are supported, except for floating point. For future improvements and additions, Sol-1’s OS will get more features added, and the first major software to be ported to the Sol-1 should be Colossal Cave Adventure and similar text-based adventure (dungeon) games.

A Heathkit H8 in which hides an 8008 instead of the normal 8080

Downgrade Your Heathkit H8 To The World’s First 8-bit Microprocessor

September 6, 2023 by Julian Scheffers 10 Comments

Typically when you’re replacing parts in an old computer it’s either for repairs or an upgrade. Upgrades like adding a more capable processor to an old computer are the most common, and can help bring an old computer a bit closer to the modern era. [Dr. Scott M. Baker] had a different idea, when he downgraded a Heathkit H8 from an 8080 to an 8008.

Despite the very similar numbers, the 8080 runs at four to nearly sixteen times the speed of its predecessor. In addition to this, the 8008 is far less capable on multiple fronts like address space, I/O ports, the stack and even interrupts. The 8008 does have one thing going for it though: the 8008 is widely known as the world’s first 8-bit microprocessor.

A green circuit board with an 8008 and supporting electronics. — The custom 8008 CPU board for the Heathkit H8.

In the video after the break, [Scott] goes into great detail about the challenges presented in replacing the 8080 with the 8008, starting with the clock. The clock is two-phase, so that what would otherwise be a single oscillator now also has a clock divider and two NAND gates.

Boring clock stuff aside, he does some great hacking using the I/O ports including expanding the I/O port count from 32 to the full 256, bit-banging serial, implementing an interrupt controller and even memory mapping 64 KiB into 16 KiB of address space! With that and a few more special adapter circuits, we think [Scott] has done a great job of downgrading his H8 and the resulting CPU board looks fabulous.

Maybe you’re wondering what happens if you upgrade the computer instead of the CPU? What you get is this credit-card sized 6502 computer.

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Fujitsu Proprietary Keyboard Goes PS/2 With A Pico

July 1, 2023 by Jonathan Bennett 8 Comments

One of our favorite retro-computing YouTubers, [Clint] from LGR, found himself a very interesting Fujitsu keyboard while thrift store shopping. It was a beautiful unit, but confusing, as this keyboard comes with an 8-pin DIN connector. A 5-pin DIN plug or 6-pin Mini-DIN would be easy to work with, but what was this odd connection? Turns out the Fujitsu N860-2500-T111 came with an Olympus CV-100 Video Processor, which was designed for medical imaging, potentially among other uses. And as often happened with old specialized hardware, the keyboard used a proprietary protocol for sending keystrokes.

[Clint] put out a call for anyone that could help him build an adapter, and [Andy] from Element14 answered the call. But this problem requires more than an adapter, mainly because the Fujitsu doesn’t have key rollover. It’s one key at a time, and that just doesn’t work for the sort of things [Clint] shows off on LGR. So, the electronic guts of the keyboard were removed, to be replaced with a Raspberry Pi Pico, wired directly to the keyboard matrix.

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IBM PalmTop Running Modern (Modified) Linux

February 6, 2022 by Bryan Cockfield 19 Comments

The handheld computing market might seem dominated by smartphones today, but before their mass adoption there were other offerings for those who needed some computing power on-the-go. If a 90s laptop was too bulky, there was always the IBM PalmTop which packed punch for its size-to-weight ratio, and for the era it was created in. [Mingcong Bai] still has one of these antiques and decided to see if it was still usable by loading a customized Linux distribution on it.

The PalmTop sported modest hardware even for its time with an Intel 486SL running at 33 MHz with 20 MiB of RAM. This one also makes use of a 1 GB CompactFlash card for storage and while [Mingcong Bai] notes that it is possible to run Windows 95 on it, it’s not a particularly great user experience. A Linux distribution customized for antique hardware, AOSC/Retro, helps solve some of these usability issues. With this it’s possible to boot into a command line and even do some limited text-based web browsing as long as the Ethernet adapter is included.

While the computer is running at its maximum capacity just to boot and perform basic system functions, it’s admirable that an antique computer such as this still works, especially given its small size and limited hardware functionality. If you’re curious about more PalmTop-style computers, take a look at the first one ever produced: the HP-200LX.

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A composite of a disassembled and reassembled Model F keyboard

Model F Keyboard Restoration Goes The Extra Mile

October 8, 2021 by Chris Wilkinson 19 Comments

The IBM Model F keyboard should need no introduction. Famed for its buckling spring key mechanisms, the Model F is lusted over for its satisfying typing experience and Armageddon-proof build quality. First introduced in 1981, many of these keyboards will now naturally require basic maintenance. However, [Epictronics] recently went a step further and restored a Model F to like-new condition.

Missing keycaps were the least of his worries, as both new and old replacements are relatively easy to come by. [Epictronics] was more concerned about the forty-year-old foam sandwiched tight inside the keyboard, most likely having long since degraded. Apart from being plain gross, the decaying foam has the potential to foul the buckling spring switches. After taking apart the body and removing the ‘disgusting’ foam pad, a replacement was forged from neoprene and a handy-dandy hole punch.

Disassembly of the keyboard case required the gentle touch of a mallet, and reassembly needed similarly inappropriate tools. As demonstrated in this vintage clip from IBM, keyboard assembly was (and still is) performed automatically by robots, driven by an IBM Series/1 minicomputer. These robots were equally impressive for their precision and strength. Without access to IBM’s aptly named ‘closing tool’ and various other robotic helpers, [Epictronics] had to settle for pool noodles and a comically large clamp during reassembly, mixed with sheer determination.

Other neat tricks in the video include applying heat to reform the coiled keyboard cable, and using car polish to clean the case plastics. The latter has the potential to make things worse, so a delicate hand is needed to maintain the textured plastic.

We recently covered another Model F restoration, and it’s exciting to see so many dedicated hackers keeping these keyboards clickety-clacking well into the 21st century.

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You Got Something On Your Processor Bus: The Joys Of Hacking ISA And PCI

January 6, 2021 by Maya Posch 32 Comments

Although the ability to expand a home computer with more RAM, storage and other features has been around for as long as home computers exist, it wasn’t until the IBM PC that the concept of a fully open and modular computer system became mainstream. Instead of being limited to a system configuration provided by the manufacturer and a few add-ons that really didn’t integrate well, the concept of expansion cards opened up whole industries as well as a big hobbyist market.

The first IBM PC had five 8-bit expansion slots that were connected directly to the 8088 CPU. With the IBM PC/AT these expansion slots became 16-bit courtesy of the 80286 CPU it was built around. These slots could be used for anything from graphics cards to networking, expanded memory or custom I/O. Though there was no distinct original name for this card edge interface, around the PC/AT era it got referred to as PC bus, as well as AT bus. The name Industry Standard Architecture (ISA) bus is a retronym created by PC clone makers.

With such openness came the ability to relatively easy and cheaply make your own cards for the ISA bus, and the subsequent and equally open PCI bus. To this day this openness allows for a vibrant ecosystem, whether one wishes to build a custom ISA or PCI soundcard, or add USB support to a 1981 IBM PC system.

But what does it take to get started with ISA or PCI expansion cards today? Continue reading “You Got Something On Your Processor Bus: The Joys Of Hacking ISA And PCI” →