Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Typo

November 18, 2024 by Kristina Panos 15 Comments

Ceci n’est pas une keyboard, sure. But it’s keyboard-adjacent, and how. [Joshua Bemenderfer]’s wrists are tired of moving off the keyboard in order to mouse, and he decided to create a trackball that can sit just below the Space bar. The idea is to get rid of the regular mouse entirely if this works out.

A split keyboard with a DIY trackball beneath the Space bar. — Image by [Joshua Bemenderfer] via Hackaday.IO

And sure, the Ploopy family of open-source mice would welcome him with open arms, but they don’t come cheap. [Joshua]’s plan here is to make something for under $10. Ideally, less than $5.

Starting with an off-the-shelf trackball, the first BOM came in around $25 if you throw in $5 for the 3D printing of the case. [Joshua] added some cheap ceramic bearings to make it better. Since this was still too high, he turned to the internals of cheap mice.

Trial and error has resulted in a 99-cent special from Ali being the idea candidate. There are even cheaper mice to be had, but this one has an ideal layout for doing a bit of surgery. It also requires remapping since [Joshua] is flipping the sensor upside down and using a POM ball on top of it. Now he just needs to figure out how to add buttons and make them split keyboard-friendly.

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Ruined 1993 ThinkPad Tablet Brought Back From The Brink

November 18, 2024 by Lewin Day 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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Overhead photo of a Tandon TM100-1 Floppy Drive and a 5,25" Floppy

How To Revive A Tandon Floppy Drive

October 4, 2024 by Heidi Ulrich 9 Comments

In this episode of [Adrian’s Digital Basement], we dive into the world of retro computing with a focus on diagnosing and repairing an old full-height 5.25-inch floppy drive from an IBM 5150 system. Although mechanically sound, the drive had trouble reading disks, and Adrian quickly set out to fix the issue. Using a Greaseweazle—a versatile open-source tool for floppy disk diagnostics—he tests the drive’s components and explores whether the fault lies with the read/write head or electronic systems.

The repair process provides fascinating insights into the Tandon TM100-1 floppy drive, a key player in vintage computing. Adrian explains how the drive was designed as a single-sided unit, yet hints at potential double-sided capability due to its circuit board, raising possibilities for future tweaks. Throughout the video, Adrian shares handy tips on ensuring proper mechanical maintenance, such as keeping lubrication in check and ensuring correct spring tension. His attention to detail, especially on termination resistors, provided vital knowledge for anyone looking to understand or restore these old drives.

For fans of retro tech, this episode is a must-watch! Adrian makes complex repairs accessible, sharing both technical know-how and nostalgic appreciation. For those interested in similar hacks, past projects like the Greaseweazle tool itself or other Amiga system repairs are worth exploring. To see Adrian in action and catch all the repair details, check out the full video.

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IBM’s 1969 Educational Computing

September 11, 2024 by Alexander Rowsell 8 Comments

IBM got their PCs and PS/2 computers into schools in the 1980s and 1990s. We fondly remember educational games like Super Solvers: Treasure Mountain. However, IBM had been trying to get into the educational market long before the PC. In 1969, the IBM Schools Computer System Unit was developed. Though it never reached commercial release, ten were made, and they were deployed to pilot schools. One remained in use for almost a decade! And now, there’s a new one — well, a replica of IBM’s experimental school computer by [Menadue], at least. You can check it out in the video below.

The internals were based somewhat on the IBM System/360’s technology. Interestingly, it used a touch-sensitive keypad instead of a traditional keyboard. From what we’ve read, it seems this system had a lot of firsts: the first system to use a domestic TV as an output device, the first system to use a cassette deck as a storage medium, and the first purpose-built educational computer. It was developed at IBM Hursley in the UK and used magnetic core memory. It used BCD for numerical display instead of hexadecimal or octal, with floating point numbers as a basic type. It also used 32-bit registers, though they stored BCD digits and not binary. In short, this thing was way ahead of its time.

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Mainframe Chip Has 360MB Of On-Chip Cache

September 8, 2024 by Al Williams 29 Comments

It is hard to imagine what a mainframe or supercomputer can do when we all have what amounts to supercomputers on our desks. But if you look at something like IBM’s mainframe Telum chip, you’ll get some ideas. The Telum II has “only” eight cores, but they run at 5.5 GHz. Unimpressed? It also has 360 MB of on-chip cache and I/O and AI accelerators. A mainframe might use 32 of these chips, by the way.

[Clamchowder] explains in the post how the cache has a unique architecture. There are actually ten 36 MB L2 caches on the chip. There are eight caches, one for each core, plus one for the I/O accelerator, and another one that is uncommitted.

A typical CPU will have a shared L3 cache, but with so much L2 cache, IBM went a different direction. As [Clamchowder] explains, the chip reuses the L2 capacity to form a virtual L3 cache. Each cache has a saturation metric and when one cache gets full, some of its data goes to a less saturated cache block.

Remember the uncommitted cache block? It always has the lowest saturation metric so, typically, unless the same data happens to be in another cache, it gets moved to the spare block.

There’s more to it than that — read the original post for more details. You’ll even read speculation about how IBM managed a virtual L4 cache, across CPUs.

Cache has been a security bane lately on desktop CPUs. But done right, it is good for performance.

IBM’s Latest Quantum Supercomputer Idea: The Hybrid Classical-Quantum System

August 28, 2024 by Maya Posch 15 Comments

Although quantum processors exist today, they are still a long way off from becoming practical replacements for classical computers. This is due to many practical considerations, not the least of which are factors such as the need for cryogenic cooling and external noise affecting the system necessitating a level of error-correction which does not exist yet. To somewhat work around these limitations, IBM has now pitched the idea of a hybrid quantum-classical computer (marketed as ‘quantum-centric supercomputing’), which as the name suggests combines the strengths of both to create a classical system with what is effectively a quantum co-processor.

IBM readily admits that nobody has yet demonstrated quantum advantage, i.e. that a quantum computer is actually better at tasks than a classical computer, but they figure that by aiming for quantum utility (i.e. co-processor level), it could conceivably accelerate certain tasks for a classical computer much like how a graphics processing unit (GPU) is used to offload everything from rendering graphics to massively parallel computing tasks courtesy of its beefy vector processing capacity. IBM’s System Two is purported to demonstrate this when it releases.

What the outcome here will be is hard to say, as the referenced 2023 quantum utility demonstration paper involving an Ising model was repeatedly destroyed by classical computers and even trolled by a Commodore 64-based version. Thus, at the very least IBM’s new quantum utility focus ought to keep providing us with more popcorn moments like those, and maybe a usable quantum system will roll out by the 2030s if IBM’s projected timeline holds up.

Making Intel Mad, Retrocomputing Edition

June 9, 2024 by Bryan Cockfield 20 Comments

Intel has had a deathgrip on the PC world since the standardization around the software and hardware available on IBM boxes in the 90s. And if you think you’re free of them because you have an AMD chip, that’s just Intel’s instruction set with a different badge on the silicon. At least AMD licenses it, though — in the 80s there was another game in town that didn’t exactly ask for permission before implementing, and improving upon, the Intel chips available at the time.

The NEC V20 CPU was a chip that was a drop-in replacement for the Intel 8088 and made some performance improvements to it as well. Even though the 186 and 286 were available at the time of its release, this was an era before planned obsolescence as a business model was king so there were plenty of 8088 systems still working and relevant that could take advantage of this upgrade. In fact, the V20 was able to implement some of the improved instructions from these more modern chips. And this wasn’t an expensive upgrade either, with kits starting around $16 at the time which is about $50 today, adjusting for inflation.

This deep dive into the V20 isn’t limited to a history lesson and technological discussion, though. There’s also a project based on Arduino which makes use of the 8088 with some upgrades to support the NEC V20 and a test suite for a V20 emulator as well.

If you had an original IBM with one of these chips, though, things weren’t all smooth sailing for this straightforward upgrade at the time. A years-long legal battle ensued over the contents of the V20 microcode and whether or not it constituted copyright infringement. Intel was able to drag the process out long enough that by the time the lawsuit settled, the chips were relatively obsolete, leaving the NEC V20 to sit firmly in retrocomputing (and legal) history.