Exploring The Gakken FX Micro-Computer

November 18, 2024 by Alexander Rowsell 11 Comments

Early computer kits aimed at learning took all sorts of forms, from full-fledged computer kits like the Altair 8800 to the ready-made MicroBee Computer-In-A-Book. For those just wanting to dip their toes in the computing world, many low-cost computer “trainers” were released, and Japan had some awesome ones. [Jason Jacques] shows off his Gakken Micro-Computer FX-System (or is it the FX-Computer? Or maybe the FX-Micom? It seems like they couldn’t make up their minds). In any event, it was a combination microcomputer and I/O building blocks system running a custom version of the Texas Instrument TMS1100 microprocessor. Specifically designed to introduce users to the world of computing, the included guide is very detailed and includes 100 example programs and lots of information on how all the opcodes work.

This 4-bit system is similar to the Kenbak computer, with a very simple instruction set and limited address space. However, adding electronic components in plastic blocks brings this machine to a new level of interactivity. Connections can be made to and from the microcomputer block, as well as to the on-board speaker and simple input/output pins. The example circuit displayed on the front cover of the box enables the microcontroller to connect to the speaker and allows a switch to light up a small incandescent bulb. We can imagine many users wiring up all sorts of extra components to their FX-Computers, and with the advent of 3D printing, it wouldn’t be difficult to create new blocks to insert into the grid.

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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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Completing The UE1’s Paper Tape Reader And First Squiggles

November 17, 2024 by Maya Posch 1 Comment

The UE1 tape reader in its nearly finished glory. Note the resistor to regulate the motor speed. (Credit: David Lovett, Usage Electric) — The UE1 tape reader in its nearly finished glory. Note the resistor to regulate the motor speed. (Credit: David Lovett, Usagi Electric)

On today’s installment of UE1 vacuum tube computer construction, we join [David Lovett] once more on the Usagi Electric farm, as he determines just how much work remains before the project can be called done. When we last left off, the paper tape reader had been motorized, with the paper tape being pulled through smoothly in front of the photodiodes. This left [David] with the task to create a PCB to wire up these photodiodes, put an amplification circuit together (with tubes, of course) to amplify the signal from said photodiodes, and add some lighting (two 1-watt incandescents) to shine through the paper tape holes. All of this is now in place, but does it work?

The answer here is a definite kinda, as although there are definitely lovely squiggles on the oscilloscope, bit 0 turns out to be missing in action. This shouldn’t have come as a major surprise, as one of the problems that Bendix engineers dealt with back in the 1950s was effectively the same one: they, too, use the 9th hole on the 8-bit tape as a clock signal, but with this whole being much smaller than the other holes, this means not enough light passes through to activate the photodiode.

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Retro Calculator Build Proves The Space Age Isn’t What It Used To Be

November 14, 2024 by Dan Maloney 19 Comments

The common wisdom these days is that even if we wanted to get back to the Moon the way we did in the 1960s, we’d never be able to do it. Most of the blame for that usually falls on the loss of institutional knowledge thanks to skilled minds and hands that have been stilled by the passage of time, but the real kicker would be finding replacements for all the parts that we used back then that just aren’t made anymore. A similar problem exists for those seeking to recreate the circuits that graced the pages of the many magazines that catered to electronics hobbyists back in the day.

Take this “Space Age Decimal Computer” reproduction that [Bob Alexander] undertook. Smitten with the circuit after seeing our story about a 1966 article detailing its construction, he decided to roll one of his own. That proved to be far harder than he thought it would be. The original circuit, really little more than an adding machine using a rotary telephone dial as an input device, used neon lamp ring buffers for counting, The trouble is, while NE-2 neon lamps are still made, they aren’t made very precisely. That makes it difficult to build a working ring buffer, which relies on precise on and off voltages. That was even a problem back then; the author suggested buying 100 lamps and carefully characterizing them after aging them in to get the 60 lamps needed.

In the end, [Bob] settled for modifying the circuit while making the build look as close as possible to the original. He managed to track down the exact model of enclosure used in the original. The front panel is populated with a rotary dial just like the original, and the same neon lamps are used too, but as indicators rather than in ring buffers. Behind the scenes, [Bob] relied on 7400-series counters and decoders to make it all work — kudos for sticking with 1970s tech and not taking the easy way out with an Arduino.

The video below goes into more detail on the build and the somewhat kludgy operation of the machine, with a few excellent [Tom Lehrer] references and a nice Cybertruck dunk to boot.

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Building A Reproduction Apple I

November 14, 2024 by Al Williams 3 Comments

If you think of Apple today, you probably think of an iPhone or a Mac. But the original Apple I was a simple PC board and required a little effort to start up a working system. [Artem] has an Apple I reproduction PCB, and decided to build it on camera so we could watch.

For the Apple I, the user supplied a keyboard and some transformers, so [Artem] had to search for suitable components. He wisely checks the PCB to make sure there are no shorts in the traces. From there, you can watch him build the machine, but be warned: even with speed ups and editing, the video is over an hour long.

If you want to jump to the mostly working device, try around the 57-minute mark. The machine has a basic ROM monitor and, of course, needs a monitor. There was a small problem with memory, but he eventually worked it out by inhibiting some extra RAM on the board. Troubleshooting is half of the battle getting something like this.

Want to look inside the clock generator chip? Or skip the PCB and just use an FPGA.

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A Teletype By Any Other Name: The Early E-mail And Wordprocessor

November 13, 2024 by Al Williams 40 Comments

Some brand names become the de facto name for the generic product. Xerox, for example. Or Velcro. Teletype was a trademark, but it has come to mean just about any teleprinter communicating with another teleprinter or a computer. The actual trademark belonged to The Teletype Corporation, part of Western Electric, which was, of course, part of AT&T. But there were many other companies that made teleprinters, some of which were very influential.

The teleprinter predates the computer by quite a bit. The original impetus for their development was to reduce the need for skilled telegraph operators. In addition, they found use as crude wordprocessors, although that term wouldn’t be used for quite some time.

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Remember The Tri-Format Floppy Disk?

November 12, 2024 by Lewin Day 15 Comments

These days, the vast majority of portable media users are storing their files on some kind of Microsoft-developed file system. Back in the 1980s and 1990s, though, things were different. You absolutely could not expect a floppy disk from one type of computer to work in another. That is, unless you had a magical three-format disk, as [RobSmithDev] explains.

The tri-format disk was a special thing. It was capable of storing data in Amiga, PC, and Atari ST formats. This was of benefit for cover disks—a magazine could put out content for users across all three brands, rather than having to ship multiple disks to suit different machines.

[RobSmithDev] started investigating by reading the tri-format disk with his DiskFlashback tool. The tool found two separate filesystems. The Amiga filesystem took up 282 KB of space. The second filesystem contained two folders—one labelled PC, the other labelled ST. The Atari ST folder contained 145KB of data, while the PC folder used 248 KB. From there, we get a breakdown on how the data for each format is spread across the disk, right down to the physical location of the data. The different disk formats of each system allowed data to be scattered across the disk such that each type of computer would find its relevant data where it expected it to be.

It’s a complex bit of disk engineering that allowed this trick to work, and [Rob] explains it in great detail. We love nitty gritty storage hacks around here. Video after the break.

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