This tiny model of a big IBM 1401 computer from 1959 is so great

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I wanna see Tiny Chef using that!


Yep! Another wonderful thing!



I was half expecting that it was a working computer (with orders of magnitude more processing power than the original). Amazing attention to details.


Given the size of surface mount components , a working scale model is theoretically possible. 0402 transistors, etc that are 1mmx0.6mm are not hard to find.


I’m almost ready to give up getting a cardboard IMSAI 8080 to print up correctly so I can start cutting. It’s inspiring to see someone’s successes even if I’m not having much luck on my own project.

Looks like all systems are GO for Major Matt Mason,
America’s Man In Space!

They should put a Raspberry Pi in it, and load it with SIMH’s 1401 emulator.


Presumably we have the technology these days to build a working miniature?

But can it run Doom?


His next project should be to build a room-size model of a Raspberry Pi.


In terms of the actual computing, “yes” would be a ridiculous understatement.

If we crudely equate 1401 i/o cycles (87,000 per second) with the “clock cycles” of a modern 7nm CPU like the Apple A12 (2,500,000,000 per second), and the 1401’s volume (guessing 1,200,000cm3) with the volume of a packaged A12 (let’s say 1cm3), then the size of a 1401 using modern technology would be about 0.035mm3, or the size of a grain of salt. This doesn’t account for storage, output devices etc., but the 1401 itself doesn’t have any of those things. And I didn’t count the separate RAM chips for the A12, but then even its on-die caches have at least 256x the capacity of a 1401’s core memory. (Also, we’re ignoring the A12’s five other processing units).

So the limits on a “working” scale model would be the bits that interface with the rest of the world. At 1/12 (dollhouse) scale, it’d be about 12.5cm tall (I think), so it might not even be big enough for whatever giant connectors a real sixties computer would use to talk to printers and tape drives and what not. But if you built the matching printer or tape drive, I guess you’d just use low-profile USB cables with countersunk jacks so they looked about right when plugged in.

For a dollhouse-scale IBM 729 tape drive, you could rework a Sony NT micro cassette recorder. The NT format used 1/10" tape, and the 729 used 1/2" tape, so it would actually be twice as wide as it really should be. If you shaved down the tape, I think it would be hard to make it work because that’s a digital, helical-scan format. So if you really wanted 1/24" tape, it might be better to slice up an ordinary cassette tape; that would probably still work, because a single track on a standard 4-track cassette is only 1/16" wide.

A card reader would not be too difficult, though you’d have to make a kind of jig to laboriously punch the teeny cards with a needle and that wouldn’t be fun. Card-punch operating was notorious for driving folk insane, even at normal size, and even with a keyboard-based punching machine.

A working 1/12 scale IBM 1403 printer would be difficult. I mean, you could probably rework a thermal printer from a cash register, but to make it authentic enough to be worth doing, you’d need something with actual letters cast out of metal, and that would involve a lot of tiny custom mechanical parts. I suppose it could just about be done with a nice desktop CNC machine like the one sitting right next to me but no, that’s going too far.

Still, a working tape drive would really sell it. I am almost persuaded this is worth trying. Except of course it would be a System/360, not a 1401.


I was also totally expecting it to be fully working :nerd_face:
2020 is so disappointing.

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I wonder how the square-cube law would affect cooling issues.

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The heat flux between an object and its surroundings is proportional to its surface area, so all things being equal, the square-cube law means scaling a component by 50% results in 25% of the heat flux for a given temperature gradient, so it will run four times as hot (relative to ambient temperature) at equilibrium.

But smaller semiconductors are more efficient, and modern semiconductors are more efficient on top of that, and thermal design has improved. Also, when you’re talking about a very complicated circuit, the total length of wire scales more like volume than length, so the resistive component of heating (which is probably significant in something like a 1401) will scale as the cube of the linear scale.

Not that I’ve done any math. But your phone is more powerful than all the world’s computers put together up to the early sixties, and it doesn’t even have a fan.


Wow, the guy is named James Newman. So close to John von Neumann!

You know, an actual bug could really mess with these.


That’s delightful! I imagine it’s big enough to act as a case for a Raspberry Pi or the like.

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