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.
My 5th / 6th grade teacher back in 1961-63 had one of these – it’s where I “cut my teeth” on digital logic.
Thanks for posting this. I am currently working on a motorized version of the rotary switch, but it’s probably a few weeks away yet.
Cool, please keep us posted on progress. I suspect a 3D-printed, motorized rotary switch will be a useful thing.
huh my dad had one like this but it had banana plugs for the interconnect
He might have had a Minivac 6010. Based on what I have read the 610 used taper pins and the 6010 had “advanced cables with resistors and capacitors”. Having neither machine it’s hard for me to say for sure, and any picture of the cables that I have found have been too fuzzy to make a determination (despite what the show on CSI :-)
Like to see one in operation too. Hey those are modern relays! Those are clearly modern videogame style pushbuttons. For realism they should be mildy uncomfortable to push and stick or resist when lateral pressure applied. Not feeling the faith. Ha.
Was gonna link some of the scams this and other relay ladder logics trainers were used in late 60s and up to sell bogus ‘Advance Computer Systems’ to small business but is somewhere under all the other fraud. This trainer wasnt scam to be clear but for what you actually got for the money… gray.
Then theres awful shit that I still hold as a scam on kids and their well intentioned but misinformed parents:
https://uedata.amazon.com/Vintage-Radio-Shack-Science-Computer/dp/B01242MSZ6
You have a sharp eye. The places where the replica diverges from the original are all called out in the project’s introduction.
OMG you mean the marketing people oversold these products back in the 60’s! Boy I’m sure glad we’ve cleaned up that mess I’m modern times.
I can only speak for the Minivac 601, but there is an enormous amount to educational value in the six manuals that shipped with the product. The device may be a little light weight by today’s standards but the training value was great.
The manuals were the only real value. The design and material were copied by most the big boys and slighlty modified and used in ‘in house training’. I assume the plan was to sell to educational venues for that price but severely underestimated cheap bastards. Towards the eighties was more of a one day idiot check evaluation device.
Haaaa ha ha. Ya all cleared up. OverMarketing and overpriced educational products after the 60s dont exist. Mermaids agree but unicorn shaking heads ‘no’ and neighing/ naying. HERO ET-18 just says “rEAdY”.
There is a Seventh manual, MINIVAC 601/6010 Book VII. But I don’t have one at this time.
It’s amazing that a machine so simple (only six relays) can play an unbeatable game of tic tac toe even if play is restricted to the machine going first each time.
There was some gimmick to that though want there? Like if you numbered the squares in a certain way (a spiral maybe?), start by taking square #1, then whatever square your opponent takes, skip up N steps from there, then take the first open square you find? Just about implementable with six relays and a rotary sequencer. But I forget what the numbering pattern was, and what N was..