Raspberry Pi Hitches Ride Inside Vintage Terminal

When a dumpster dive yielded a vintage video display terminal, [dennis1a4] knew just what to do — bring the Heathkit H19 back to life and stuff a Raspberry Pi inside.

The early days of the personal computer era were a time of great market diversity. Everyone was making stuff needed to cobble together your perfect computer, and terminals were among the most important pieces of gear. Lear Siegler, DEC, Wyse — everyone was in on the game. Even Heathkit competed with its H19 serial terminal, which would have set you back a thousand or so early-1980s dollars.

The terminal [dennis1a4] found was DOA, but he quickly determined that a bad cap was shorting out the -12VDC rail. A little extra detective work was needed to get the terminal to both echo characters locally and output them over the RS-232 port, and bam, working terminal. But then what? Raspberry Pi to the rescue! But those old school +/-12 volts swings would give a Pi a bad case of Blue Smoke Disease. After a little voltmeter poking, and through the magic of socketed driver chips, the Pi was talking right to the terminal at a screaming 9600 baud and accessing the Hackaday Retro site on the 80-by-24 mono display.

All in all, a nice hack on a piece of computer history. But just one question: Can it play Doom Flappy Bird?

Reinventing The Harwell Dekatron

A huge number of modern replicas of retro computers pass our screens here at Hackaday, and among them are an astonishing variety of technologies. Those who weren’t lucky enough to be present in the days when the building blocks of computing were coming together may have missed out on understanding gate-level operation of a computer. Put your super-powerful and super-complex systems-on-chip aside sometime and dig into the details of their distant ancestors.

Most such machines follow a very conventional architecture, so it is something of a surprise to find a project recreating a modern version of something far more obscure. The Harwell Dekatron, also known as the WITCH, can be found at the National Museum Of Computing in Bletchley, UK, and [David Anders] is building a modern all-electronic replica of it.

The original machine is currently the world’s oldest working digital computer, a hybrid electromechanical computer built at the start of the 1950s  to perform calculations for British nuclear scientists. It was retired by the end of that decade and found its way — via a technical college, a museum, and a period of storage in a council archive — to Bletchley where it was restored to working order by 2012. Its special feature is the use of dekatron discharge tubes as memory, allowing an instant visual display of its working as it happens.

[David]’s replica uses modern logic chips to replicate the building blocks of the Harwell Dekatron, and his write-up is as fascinating for that as it is for his study of the real thing in the museum. We ran into [Dave] showing off this project at the Hackaday Dallas event last year and are excited to learn of the advancements since then from his Hackaday.io page. He’s put his research and designs on GitHub, and a series of YouTube videos, the introduction to which we’ve put below the break.

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A Clock Created with Conway’s Life

Conway’s life has to be the most enduring zero-player computer game in history. Four simple cellular automaton rules have been used to create amazing simulations since the 1970’s. The latest is an entire digital clock implemented in life. StackExchange user [dim] created this simulation in response to a challenge from [Joe Z]. We have to admit that we didn’t believe it at first, but you can run it yourself by importing [dim’s] gist to the online Javascript Conway’s Life Simulator. To say this is impressive would be an understatement. We don’t know exactly how long it took [dim] to build this clock, but the challenge has been around since August of 2016.

[Dim] does a pretty good job of describing exactly how the clock works. The timebase is at the top. Below it is clock distribution and counters. After that come counters, latches, and lookup tables. Data moves around the clock in the form of gliders. P30 (aka Queen Bee) gliders to be exact. It might make things simpler to think of the glider paths as circuit traces, and the gliders themselves as clock pulses.

We couldn’t get over all the little details in this design. If you zoom way in, you can see all the lookup table patterns have been annotated, much in the way a schematic would be. For [Dim’s] next feat, we hope he takes on [Joe Z’s] Tetris challenge!

Conway’s life is like honey for hackers. We’ve seen it running on our own Hackaday Badge. We’ve even seen clocks that run the game on their display. Someone needs to implement a clock that runs the game that runs this clock. Clockception, anyone?

Light Replaces Electrons for Giant Vector-Graphics Asteroids Game

For all its simplicity, the arcade classic Asteroids was engaging in the extreme, with the ping of the laser, the rumble of the rocket, the crash of crumbling space rocks, and that crazy warble when the damn flying saucers made an appearance. Atari estimates that the game has earned operators in excess of $500 million since it was released in 1979. That’s two billion quarters, and we’ll guess a fair percentage of those coins came from the pockets of Hackaday’s readers and staff alike.

One iconic part of Asteroids was the vector display. Each item on the field was drawn as a unit by the CRT’s electron beam dancing across the phosphor rather than raster-scanned like TV was at the time. The simple graphics were actually pretty hard to create, and with that in mind, [standupmaths] decided to take a close look at the vector display of Asteroids and try to recreate it using a laser.

To be fair, [Seb Lee-Delisle] does all the heavy lifting here, with [standupmaths] providing context on the history and mathematics of the original vector display. [Seb] is a digital artist by trade, and has at the ready a 4-watt RGB laser projector for light shows and displays. Using the laser as a replacement for the CRT’s electron beam, [Seb] was able to code a reasonably playable vector-graphic version of Asteroids on a large projections screen. Even the audio is faithful to the original. The real treat comes when the laser is slowed and a little smoke added to show us how each item is traced out in order.

All [Seb]’s code is posted on GitHub, so if you have a laser projector handy, by all means go for it. Or just whip up a custom vector display for your own tabletop version of Asteroids.

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Simple Marble Machine Captivates the Eyes

Marble machines are the kind of useless mechanisms that everybody loves. Their sole purpose is to route marbles through different paths for your viewing pleasure. They can be extremely complicated contraptions, and sometimes that is the precisely the point. However, even a simple mechanism can be delightful to watch. [Denha] just uploaded his latest creation, using a spring as elevator and a simple zig-zag path.

The construction is relatively simple, a spring with the appropriate pitch for the steel balls size is used as an elevator. The spring is driven by a small electric motor via a couple of gears, and a wooden zig-zag path for the marbles lies next to the spring. The marbles go up with the spring and return in the wooden path in an endless journey.

We believe that a serious hacker should build a marble machine at least once in their life. We have posted several of them, from simple ones to other more complicated designs that require careful craftsmanship. [Denha]’s Youtube channel is full of good ideas to inspire your first project. In any case, watching a marble machine at work is quite a nice, relaxing experience.

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Wimshurst Machines: High Voltage from the Gods

Wimshurst machine demo
Wimshurst machine demo

The Wimshurst machine is one of the oldest and best known electrostatic machines, consisting of its iconic two counter rotating disks and two Leyden jars. Most often you see someone hand cranking it, producing sparks, though we’ve seen it used for much more, including for powering a smoke precipitator for cleaning up smoke and even for powering a laser.

It works through an interesting sequence of events. Most explanations attempt to cram it all into one picture, requiring some major mental gymnastics to visualize. This often means people give up, resigned to assume these work through some mythical mechanics that defy a mortal’s ability to understand.

So instead, let’s do a step-by-step explanation.

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Raiders of the Lost OS: Reclaiming A Piece of Polish IT History

In today’s digital era, we almost take for granted that all our information is saved and backed up, be it on our local drives or in the cloud — whether automatically, manually, or via some other service.  For information from decades past, that isn’t always the case, and recovery can be a dicey process.  Despite the tricky challenges, the team at [Museo dell’Informatica Funzionante] and [mera400.pl], as well as researchers and scientists from various museums, institutions, and more all came together in the attempt to recover the Polish CROOK operating system believed to be stored on five magnetic tapes.

MEERA-400 Tape Recovery 1

Originally stored at the Warsaw Museum of Technology, the tapes were ideally preserved, but — despite some preliminary test prep — the museum’s tape reader kept hanging at the 800 BPI NRZI encoded header, even though the rest of the tape was 1600 BPI phase encoding. Some head scratching later, the team decided to crack open their Qualstar 1052 tape reader and attempt to read the data directly off the circuits themselves!!

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