Minivac

3 Articles

Recreating Retrocomputers Hack Chat

August 10, 2020 by 1 Comment

Join us on Wednesday, August 12 at noon Pacific for the Recreating Retrocomputers Hack Chat with Mike Gardi!

Building the first commercial computers in the late 1950s and early 1960s was certainly a complex a task, but building the computer industry was even harder. Sure, engineers were already getting on board with designing in silicon and germanium instead of glass and tungsten, and all digital circuits are really just abstractions of analog designs most of them were already familiar with. But what about all the other people who would need to get up to speed on the workings of digital computers? What good is a tool if the only people who know how to use it art the ones who built it?

To make computers make money, companies needed legions of installers, operators, programmers, marketers, and salespeople, and all of them needed training. And so early computer companies put a lot of effort into building training devices to get people up to speed. These trainers helped teach everything from basic logic circuits and Boolean relationships to simple programming concepts, and each of them contributed in their own way to developing the computer industry that we know today.

Mike Gardi has a unique hobby: among other things, he builds faithful replicas of some of the nicer examples of these lost bits of computing history. His reproduction of Claude Shannon’s Minivac 601 trainer is a great example of the art, as is the DEC H-500 Computer Lab build he’s currently working on. Along the way, he’s explored some side alleys on the road to our computerized world, like Dr. Nim and the paperclip computer. All his builds are lovingly created from 3D-prints and really capture the essence of the toys and tools of the time.

Join us as we take a trip inside this niche realm of retrocomputing and find out why Mike finds it fascinating enough to devote the time it obviously takes to build such exacting replicas. We’ll talk about what projects he’s got going on right now, what he has planned for the future, and maybe even dive into some of his secrets for such great looking 3D prints.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, August 12 at 12:00 PM Pacific time. If time zones baffle you as much as us, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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Minivac 601 Replica Gets A Custom Motorized Rotary Switch

July 13, 2019 by 2 Comments

One of the joys of electronics as a hobby is how easy it is to get parts. Literally millions of parts are available from thousands of suppliers and hundreds of distributors, and everyone competes with each other to make it as easy as possible to put together an order from a BoM. If you need it, somebody probably has it.

But what do you do when you need a part that doesn’t exist anymore, and even when it did was only produced in small numbers? Easy – you create it yourself. That’s just what [Mike Gardi] did with this unique motorized rotary switch he needed to complete his replica of a 1960s computer trainer. We covered his build of the Minivac 601, a trainer from the early computer age that let experimenters learn the ropes of basic digital logic. It used mostly relays, lamps, and switches connected by jumpers, but it had one critical component – a rotary control that was used for input and, with the help of a motor, as an output indicator.

[Mike]’s version of the switch is as faithful to the original as possible, at least in terms of looks. The parts are mostly 3D-printed, with 16 reed switches embedded in the walls and magnets placed in the rotor. The motor to operate the rotor is a simple gear motor mounted to a hinged bracket; when the rotor needs to move, a solenoid pulls the motor’s friction drive wheel up against the rotor.

The unique control slots right into the Minivac replica and really completes the look and feel. Hats off to [Mike] for a delightful replica of a lost bit of computer history and the dedication to see it through to completion.

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A Faithful Replica Of An Early Computer Trainer

June 17, 2019 by 11 Comments

Turn the clock back six decades or so and imagine you’re in the nascent computer business. You know your product has immense value, but only to a limited customer base with the means to afford such devices and the ability to understand them and put them to use. You know that the market will eventually saturate unless you can create a self-sustaining computer culture. But how does one accomplish such a thing in 1961?

Enter the Minivac 601. The brainchild of no less a computer luminary than Claude Shannon, the father of information theory, the Minivac 601 was ostensibly a toy in the vein of the “100-in-1” electronics kits that would appear later. It used electromechanical circuits to teach basic logic, and now [Mike Gardi] has created a replica of the original Minivac 601.

Both the original and the replica use relays as logic switches, which can be wired in various configurations through jumpers. [Mike]’s version is as faithful to the original as possible with modern parts, and gets an extra authenticity boost through the use of 3D-printed panels and a laser-cut wood frame to recreate the look of the original. Sadly, the unique motorized rotary switch, used for both input and output on the original, has yet to be fully implemented on the replica. But everything else is spot on, and the vintage look is great. Extra points to [Mike] for laboriously recreating the original programming terminals with solder lugs and brass eyelets.

We love seeing this retro replica, and appreciate the chance to reflect on the genius of its inventor. Our profile of Claude Shannon is a great place to start learning about his other contributions to computer science. We’ve also got a deeper dive into information theory for the curious.

Thanks to [Granz] for the tip.