Respectfully Modifying The Amiga 500

March 12, 2018 by Tom Nardi 22 Comments

Modifying the Amiga 500 to speed up access to RAM in a memory expansion pack is a well documented procedure, with guides on the process written in the early 1990’s when the hardware was only a few years old. But as they were written for contemporary hardware, they make no concessions for how one should be treating a vintage computer that’s now over 30 years old. In 1993, cutting traces on the Amiga 500 motherboard was just a last ditch effort to eek a few more months of service life out of an outdated desktop computer. But in 2018, it’s kind of like when that old lady tried to “restore” a fresco of Jesus in Spain; it might be done with the best of intentions, but you still screwed the thing up good and proper.

Such things don’t fly over at [Inkoo Vintage Computing]. There you can find a guide that details the impressive lengths one can go to if they want to perform the classic modification without any irreversible changes to the motherboard. To avoid the cut traces and soldered bodge wires, this version of the modification makes use of a novel adapter that breaks out the necessary connections on the 8372A chip.

The adapter is simply a homemade PCB with both male and female plastic leaded chip carrier (PLCC) connectors. The few pins on the chip that needed rerouting are exposed as solder pads on the adapter for easy wiring. There are even a couple jumpers on the adapter to turn the modifications on and off.

Not surprisingly, the trickiest part of building this adapter was sourcing the antiquated PLCC connectors. Assuming you can even find them, you are then left with the challenging task of soldering them together. Judging by the pictures on the [Inkoo Vintage Computing] page, it’s no walk in the park.

Another similar arrangement is used in the expansion bay of the Amiga, where a pin is virtually “cut” in the connector. A tiny PCB is soldered to a 3×2 header to reroute the signals, and another jumper is used to enable and disable the pin. Luckily, the long pins on the Amiga memory expansion are forgiving enough that the little board can fit in between them without breaking electrical contact.

We’re no stranger to the Amiga 500 around these parts. We’ve covered how to get the 1987-vintage machine online in the 21st century, as well as employing a Raspberry Pi to emulate the original floppy drive. You can even make your own faux-Amiga with a 3D printed case, if you suffer from a sort of existential dread when working on a computer that’s older than you are.

Next Week: Vintage Computer Festival Pacific Northwest

February 2, 2018 by Brian Benchoff 10 Comments

Next week something magical is happening. Seattle is getting a Vintage Computer Festival. It’s the Vintage Computer Festival Pacific Northwest, and it’s happening Saturday, February 10th and Sunday, February 11th at the Living Computers Museum and Labs.

As with all Vintage Computer Festivals, this is one with plenty of exhibits, speakers, and the ever-popular consignment shop. A few of the more interesting exhibits include a demonstration of the Syntauri alphaSyntauri, a synthesizer card and controller designed for the Apple II. When it was released in 1980, this was the first affordable digital synthesizer that competed against the Synclavier and Fairlight CMI. The difference? Synclaviers cost as much as a house, where the alphaSyntauri cost as much as a car. Also on deck is the dis-integrated MOnSter6502, a complete NMOS 6502 constructed out of individual, surface mount transistors. The Digi-Comp II from Evil Mad Scientist will be there, there will be BlinkenBones, and for anyone who wants to assemble their own front panel for a vintage minicomputer, [Oscar Vermeulen] will be there with the Pi-DP/8. This isn’t an event to miss.

As an aside, we’d really like to commend the Vintage Computer Federation for their incredible work in putting these shows together. The VCF West at the Computer History Museum in Mountain View is an incredible show, VCF Southeast has some amazing displays, and VCF East in New Jersey is a pretty incredible gathering going down May 18th through the 20th this year. The people working behind the scenes to make these shows happen are doing a service for all vintage computers and performing digital archeology that benefits us all.

Hackaday is proud to be a sponsor of VCF Pacific Northwest.

Another New Old Computer On An FPGA

December 1, 2017 by Al Williams 28 Comments

How would you sell a computer to a potential buyer? Fast? Reliable? Great graphics and sound? In 1956, you might point out that it was somewhat smaller than a desk. After all, in those days what people thought of as computers were giant behemoths. Thanks to modern FPGAs, you can now have a replica of a 1956 computer — the LGP-30 — that is significantly smaller than a desk. The LittleGP-30 is the brainchild of [Jürgen Müller].

The original also weighed about 740 pounds, or a shade under 336 kg, so the FPGA version wins on mass, as well. The LGP-30 owed its relative svelte footprint to the fact that it only used 113 tubes and of those, only 24 tubes were in the CPU. This was possible, because, like many early computers, the CPU worked on one bit at a time. While a modern computer will add a word all at once, this computer — even the FPGA version — add each operand one bit at a time.

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MiSTer Upgrades Vintage Computer Recreations

November 18, 2017 by Al Williams 26 Comments

The MiST project provides an FPGA-based platform for recreating vintage computers. We recently saw an upgraded board — MiSTer — with a similar goal but with increased capability. You can see a video of the board acting like an Apple ][ playing Pac Man, below.

The board isn’t emulating the target computer. Rather, it uses an FPGA to host a hardware implementation of the target. There are cores for Apple, Atari, Commodore, Coleco, Sega, Sinclair and many other computers. There are also many arcade game cores for games like Defender, Galaga, and Frogger.

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Vintage Computer Festival Switzerland This Weekend

November 18, 2016 by Brian Benchoff 5 Comments

This weekend marks the Vintage Computer Festival Europe – Switzerland, a two-day extravaganza of vintage hardware held in Zurich, Switzerland.

Of interest for this VCF will be an LGP-30 replica (a computer without RAM or ROM released in 1956), an IBM System/360 front panel, lots of blinkenlights, Swiss computers, and [Oscarv], creator of the very successful PiDP-8/I project on Hackaday.io, will be there with his minified PiDP-11/70. If you don’t have one of [Oscar]’s PiDP8 machines sitting on your desk yet, don’t worry — the 11/70 is the one you really want. It is beautiful.

As you would expect from a Vintage Computer Festival, all the standards will be there. The flea market is open, soldering stations are present, talks will be held, and very old and very rare hardware will be blinking. From our experience with Vintage Computer Festivals, Europe does it right. Last year’s festival in Munich was a blast, and this year’s celebration in Zurich looks like it will be as well.

Liberté, Égalité, Fraternité, AZERTY

April 20, 2016 by Brian Benchoff 30 Comments

In the US, we don’t hear much about computing from beyond the Anglosphere. We’ve seen some home computer clones from behind the iron curtain, but getting any information about them is hard. If you find an old keyboard with a QWERTZ layout, or even a few Cyrillic characters, in the States, it’s a rarity. To date, the only French computer on Hackaday is an old Minitel dumb terminal. To help rectify this, [Jeremie Marsin], [Thierry Mazzoleni], and [Jean Paul Mari] from Quebec brought the best of the French computing revolution of the 1980s along to this year’s Vintage Computer Festival East

The evolution of the reigning champion of this exhibit begins with the Micronique Victor Lambda, a licensed copy of a purely American computer, the Interact Home Computer System. This computer featured a 2 MHz 8080A, 8 or 16 kB of RAM, and was quickly discontinued. The French company Micronique quickly bought the original designs and remarketed the computer in France.

In a few short years, Micronique took this design and turned it into the Hector. This machine featured a 5 MHz Z80, 48 kB of RAM, high resolution graphics (243×231 at four colors) and included BASIC and Forth interpreters.

The Victor and Hector were the best home computers at the time, but for every Commodore or Apple, you need a ZX Spectrum. France’s version of this tiny computer with a terrible keyboard was the Matra Alice 32, a computer with a 1 MHz 6803, 16kB of Ram, and a real 80×25 text mode. The Alice is heavily based on the American TRS-80 MC-10, with a SCART connector and an AZERTY keyboard.

The weirdest computer [Jeremie], [Thierry], and [Jean Paul] brought out? That would be the Excelvision EXL100. The 1980s, for better or worse, were the times of the Z80 and 6502. The EXL100 was running something completely different. This home computer used a TMS7020 CPU from Texas Instruments, a speech synthesizer, and a wireless keyboard. Very strange for the time and relatively inexpensive; in 1984 this computer cost only ₣3190, or about $550 USD.

[Jeremie], [Thierry], and [Jean Paul] had an exhibit that presented the best the Francosphere had to offer to the computing world in the 80s and 90s. We haven’t seen enough early computers from outside the US, so we’re happy to have met these guys at the 11th annual Vintage Computer Festival East.

Retro TO-3 Switching Voltage Regulator

July 25, 2015 by Al Williams 33 Comments

Restoring old gear often means replacing unavailable parts with modern equivalents. [Alex Eisenhut] needed to replace some old TO-3 voltage regulators and decided to make an authentic-looking switching power supply replacement. These three pin metal cans were very common, especially the LM340 5V regulator which was, of course, a linear regulator. Today, you are more likely to see a 7805 in a TO-220 case or something surface mount for a comparable linear regulator.

As you might expect, the board uses surface mount components. [Alex] used Mill Max machine pins to match the original regulator footprint and calls the regulator Ton3y. He plans to cover it up with a 3D printed lid, but it seems a shame to hide the fine PCB work.

In the pictures, you can see that the machine pins are a tight fit. [Alex] used a hammer to lightly tap them into place. Of course, the original TO-3 regulators were linear and would generate a lot of heat. The Ton3y, as you’d expect from a switching power supply, runs cool (according to the scientific measurement made with [Alex]’s pinky finger) and surely has a wider input voltage range and more output current capacity.

We’ve seen replacement switching regulators before, but this one is really a work of art.