From Cop Car Data Terminal, To Retro Computer

It is possible that you will have lived your life without ever coming into contact with a Motorola MDT9100-T. The data terminal of choice for use in police cars across the globe was a computer with a full-sized QWERTY keyboard, a small CRT display, a mainboard sporting an Intel 386SX processor, and a custom version of Windows 3.1. [Trammell Hudson] and some friends from NYC Resistor scored some MDT9100s in an online auction and found them to be just too good an opportunity not to crack them open and see what could be done.

The custom Windows install could be bypassed with a DOS prompt for some period demoscene action, but [Trammell] wanted more. The 386SX wasn’t even quick when it was new, and this computer deserved the power of a BeagleBone! A custom cape was created on a prototyping cape to interface with the MDT9100 header carrying both keyboard and video. A bit of detective work revealed the display to be a 640×480 pixel mono VGA. The ‘Bone’s LVDS output can drive VGA through a resistor ladder DAC with the aid of an appropriate device tree overlay. The keyboard was then taken care of with a Teensy working as a USB device, resulting in a working Linux computer in the shell of an MDT9100.

It’s always good to see old technology brought up to date. Amusingly a couple of years ago we reported on the death of VGA, but retro projects like this one mean it’ll be a long time before we’ve heard the last of it.

Hijacking A Sony Watchman For Pong

The era of the vintage television was a great one, and one of the transitional by-products was the Sony Watchman. It was a portable TV which Sony started selling in 1982, and the amazing thing about it was that it had an actual 4-inch cathode ray tube or CRT. [Sideburn] just posted a video in which he hijacks the internals of a Watchman to make it into a portable game of Pong.

The hack begins with removing the TV tuner module inside to make some room for the new residents. Next comes the M51364P which is VIF video decoder chip, and for which surprisingly there is not a lot of info on the web. They were able to find a part of the schematic, which though it was in Russian may still be useful for enthusiasts. Removing the VIF revealed the audio and video pins that needed the appropriate signals for the hack to be successful. In an age of multilayer boards it is amazing how a two-layer PCB makes life so easier for the tinkerer.

For the new brains an Arduino Nano clone was selected, and instead of adding modern buttons the existing volume and band select switches were convinced to be the paddle control and play/pause button. Getting everything to fit was easy with the absence of the tuner module, and voila! New(ish) hardware. For the firmware, [Sideburn] turns to Hackvision firmware which has a host of games such as Space Invaders, Asteroids, and even Tetris.

We covered Hackvision a few years ago as a hardware/firmware bundle, and if you are more into CRTs then check out the Arduino driven 6845 CRT controller.

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Whatever Happened To The Desktop Computer?

If you buy a computer today, you’re probably going to end up with a laptop. Corporate drones have towers stuffed under their desks. The cool creative types have iMacs littering their open-plan offices. Look around on the online catalogs of any computer manufacturer, and you’ll see there are exactly three styles of computer: laptops, towers, and all-in-ones. A quick perusal of Newegg reveals an immense variety of towers; you can buy an ATX full tower, an ATX mid-tower, micro-ATX towers, and even Mini-ITX towers.

It wasn’t always this way. Nerds of a sufficient vintage will remember the desktop computer. This was, effectively, a tower tilted on its side. You could put your monitor on top, negating the need for a stack of textbooks bringing your desktop up to eye level. The ports, your CD drive, and even your fancy Zip drive were right there in front of you. Now, those days of desktop computers are long gone, and the desktop computer is relegated to history. What happened to the desktop computer, and why is a case specifically designed for a horizontal orientation so hard to find?

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Chasing the Electron Beam at 380,000 FPS

Analog TV is dead, but that doesn’t make it any less awesome. [Gavin and Dan], aka The Slow Mo Guys recently posted a video about television screens. Since they have some incredible high-speed cameras at their disposal, we get to see the screens being drawn, both on CRT and more modern LCD televisions.

Now we all know that CRTs draw one pixel at a time, drawing from left to right, top to bottom. You can capture this with a regular still camera at a high shutter speed. The light from a TV screen comes from a phosphor coating painted on the inside of the glass screen. Phosphor glows for some time after it is excited, but how long exactly? [Gavin and Dan’s] high framerate camera let them observe the phosphor staying illuminated for only about 6 lines before it started to fade away. You can see this effect at a relatively mundane 2500 FPS.

Cranking things up to 380,117 FPS, the highest speed ever recorded by the duo, we see even more amazing results. Even at this speed, quite a few “pixels” are drawn each frame. [Gavin] illustrates that by showing how Super Mario’s mustache is drawn in less than one frame of slow-mo footage. You would have to go several times faster to actually freeze the electron beam. We think it’s amazing that such high-speed analog electronics were invented and perfected decades ago.

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Why Sony’s Trinitron Tubes Were the Best

If you’re old enough to remember Cathode Ray Tube (CRT) Televisions, you probably remember that Sony sold the top products. Their Trinitron tubes always made the best TVs and Computer Monitors. [Alec Watson] dives into the history of the Sony Trinitron tube.

Sony Color TVs didn’t start with Trinitron — for several years, Sony sold Chromatron tubes. Chromatron tubes used individually charged wires placed just behind the phosphor screen. The tubes worked, but they were expensive and didn’t offer any advantage over common shadow mask tubes. It was clear the company had to innovate, and thanks to some creative engineering, the Trinitron was born.

Closeup of a Trinitron tube shows unbroken vertical stripes which led to a brighter picture.

All color TV’s shoot three electron guns at a phosphor screen. Typical color TVs use a shadow mask — a metal sheet with tiny holes cut out. The holes ensure that the electron guns hit only the red, green and blue dots of phosphor. Trinitrons use vertical bars of single phosphor color and a picket fence like aperture grille. The aperture grill blocks less of the electron beam than a shadow mask, which results in a much brighter image. Trinitrons also use a single electron gun, with three separate cathodes.

[Alec] is doing some amazing work describing early TV systems and retro consumer electronics over on his YouTube channel, Technology Connections. We’ve added him to our Must watch subscription list.

Interested in retro CRTs? Check out Dan’s article on cleaning up the fogged plastic safety screen on the front of many CRTs.

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Stromberg Carlson Charactron Tube

Flat panel TVs have spoiled us. It used to be that a big display took up a lot of room on your desk or living room because of the depth of the CRT’s electron gun. We wonder what the designers of the charactron would think if they could see our big flat screens today. Never heard of a charactron? Check out [uniservo’s] video of one of these old character display tubes.

You might think the device is just a simple small CRT. However, it is much stranger than that. Inside the tube was a stencil that contained all the characters the device could display. A deflection coil would move an electron beam to light up a particular character. Then another coil would deflect the patterned electron beam to the desired space on the screen. In some cases, the entire set of stencils would get the beam and the first deflection coil would pick which character made it through an aperture. Either way, the tube was not just a display, but a character generator.

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The Nixie Tube Killer That Never Was

With the wealth of Nixie projects out there, there are points at which Hackaday is at risk of becoming Nixieaday. Nixie clocks, Nixie calculators, Nixie weather stations, and Nixie power meters have all graced our pages. And with good reason – Nixie tubes have a great retro look, and the skills needed to build a driver are a cut above calculating the right value for a series resistor for an LED display.

But not everyone loved Nixies back in the day, and some manufacturers did their best to unseat the venerable cold cathode tubes. [Fran Blanche] came across one of these contenders, a tiny cathode ray tube called the Nimo, and after a long hiatus in storage, she decided to put the tube to the test. After detailing some of the history of the Nimo and its somewhat puzzling marketing — its manufacturer, IEE, was already making displays to compete with Nixies, and seven-segment LEDs were on the rise at the time — [Fran] goes into the dangerous details of driving the display. With multiple supply voltages required, including a whopping 1,700 V DC for the anode, the Nimo was anything but trivial to integrate into products, which probably goes a long way to explaining why it never really caught on.

If you happen to have one of these little bits of solid unobtanium, [Fran]’s video below will go a long way to bringing back its ghostly green glow. You might say that [Fran] has a thing for oddball technologies of the late 60s — after all, she’s recreating the Apollo DSKY electroluminescent display, and she recently helped a model Sputnik regain its voice.

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