The rise and fall of IBM's 4 Pi aerospace computers: an illustrated history | Hacker News Reader

The rise and fall of IBM's 4 Pi aerospace computers: an illustrated history

righto.com

100 pointszdw25 comments

This triggered a tangential memory of encountering this kind of aerospace computer box.

I was a teenage intern at a very serious software engineering company, which was doing bespoke high-end in-circuit emulators, integrated into a full-lifecycle software engineering platform.

One time I wandered into the hardware engineering area, there was a customer box looking a bit like the later-model photos in the article, just sitting on an EE bench. (Though my vague memory is that it might've been something like Honeywell or Rockwell?)

As a teen, with so may things to learn about workstation networks and software engineering, and working professionally for the first time, and becoming an adult... It was awhile before I slowly learned who were the customers for all this platform the company developed. It was for people who make complex, critical systems -- mainly military, aerospace, and datacommunications. So it was just further overwhelming wonder: people use our stuff for aircraft and spacecraft?! So cool!

Later in my career, I have more context, to decide the kinds of things I want to work on. I'm also often involved when we start with the understanding of the customer, and the building cool stuff tends to follow that. Some of the AI toys recently elicit some of that earlier wow of everything being new and cool, but now knowing more context, and seeing through some of the current marketing noise.

"it might've been something like Honeywell or Rockwell"

Right rectangular prism with MIL-STD circular connectors on one side describes almost all Cold War era hardware. Could have been anything.

Author here: I've finally finished a detailed history of IBM's 4 Pi computers, powering everything from the B-1 bomber to the Space Shuttle. Let me know if you have questions...

just one: why it named System/4 Pi ? (the Pi part especially)

The name is essentiallly a geometry joke. The IBM System/360 line of mainframes (1964) revolutionized the computer industry with the concept of one family of computers for all applications: business and scientific. (Before the 360, nobody considered compatibility, so different computer models were entirely incompatible, which was a mess.) The name symbolized that System/360 covered the full 360º of applications.

The 4 Pi name extended this idea to applications in the 3-dimensional world: 4π is the number of steradians making up a full sphere. As IBM put it, "System/4 Pi also fills a sphere—the full spectrum of military computer needs—for airborne, space, or shipboard use."

My local carwash's top-end wash is called the "Ultimate 360°", despite the fact that it obviously cleans the entire surface area of the car, and I'm simultaneously annoyed by the name and reminded of the System/4 Pi.

And a follow up, was the Raspberry Pi named as a joke reference to these?

Could a single person lift the complete set of manuals for one computer model?

And what percentage of the pages of the manual said "this page intentionally left blank"?

Are there any similar parallel series in China, France, Germany, India, Japan, Russia or the UK that you have had a chance to study?

I'd like to study aerospace systems from other countries. Unfortunately, it's even harder to get information on foreign systems than US systems.

You mentioned in the post that you "received a stack of 4 Pi marketing brochures and articles". Do you plan to scan these and place them on your website or the Internet Archive? I'd love to read them!

Amazing article. What really stands out for me besides the obviously interesting electronics details is the incredible mechanical engineering. Quite a few of the frames and frame components look as if they've been milled out of aluminum billets.

In the 70's I bought a 300A 5V IBM power supply for parts, it took a couple of hours to get it home and lug it up to my attic where I spent a few weeks disassembling it and I came away with the same impression: that thing was engineered in a way that I had not yet seen in other electronics gear that I had come across. It got me a lifetime supply of RCA 2N3055's, (the good ones, the Motorola ones were junk in comparison) as well as all manner of capacitors (sizes 'large' and 'gigantic').

IBM really knew how to engineer hardware.

Cool stuff. Worked next to these one summer at IBM on dev tools that ran on PC. But never knew much about them. They were in the thick aluminum case and you didn't touch them!

Back when I was in the USAF they told us 4 Pi was because it was essentially two IBM 360 mainframes in parallel. Probably BS but that was what we all thought.

Really happy to see this history lesson in any case, I had mostly forgotten about my experiences from the mid 90s.

You're right, that's BS :-) Yes, many of the 4 Pi systems were essentially IBM 360 mainframes; some were completely compatible, while others were more "inspired" by the 360. However, only the little-used EP/MP model was a multiprocessor system. As for the name, IBM made it clear that the name comes from 4 pi steradians in a sphere.

What 4 Pi systems did you work with, by the way? Do you have any interesting stories?

Nothing too interesting I’m afraid. The unit I was in was responsible for the 4 pi software on the E-3 AWACS. If memory serves, this was right about the time of block 30/35 rollout. I looked recently and they’re running much newer, better computers these days (it’s been 30 years, now I feel old).

We used to say that the computers were so heavy that the E-3 was routinely taking off over its maximum takeoff weight :). Another likely bit of BS. But it did take that old bird well over a minute of takeoff roll to get airborne, which is weird when you are used to airliners. I did not regularly get to ride in one, we mostly used a 4 pi in our E-3 simulator. Did a lot of “external testing” which was mostly very tedious but we did get to talk to interesting people.

The E-3's computer was definitely heavy: the brochure that I have says that it weighed 1,826 pounds. (There's a nice photo of the refrigerator-sized cabinet full of circuit boards in my article.) The 4 Pi line is kind of strange; it has all these compact 60-pound computers, and then they throw in a couple of monster systems that weigh almost a ton.

Actually I'm mistaken; the AWACS CC-2E computer was also a redundant dual processor system.

So I can continue to spread a bit of fun misinformation when someone asks (they never do) by saying that 4 pi radians is 720 degrees, or two 360s. It's a harmless bit of fun, nobody really cares enough to call me on it :).

About 360 and pi: In the late 70's, "Two Pi Corporation" of Santa Clara made S/370-clone minicomputers named V/32. In early 1981, Two Pi was acquired by Four Phase Systems of Cupertino, a maker of early PMOS cpus. Four Phase was itself acquired in late 1981 by Motorola and withered away. Four Phase's campus was leveled and replaced by Apple's Infinite Loop campus, with nearly the same footprint.

I don't know how to put it into words, but this aesthetic of computers just looks sooo good. Makes me want to try making my homelab/experimental hardware look like it. Any ideas how to source parts that look similar in low quantities?

military surplus

It's easy to get the military round connectors from Digikey; it just isn't cheap :-) eBay is your best bet for an affordable price on them.

Yeah, eBay has tons of them. Use them for movie props all the time. If anyone is in LA there are plenty of surplus electronics shops that are overflowing with them. I used to search "cannon connectors" IIRC.

The steel ones ("Cannon connectors") are indeed very expensive: the only ones I have were removed from industrial equipment. However, for hobbyist use, I'd buy CPC -- Circular Plastic Connectors. Those are available in the same variety of pinouts and cost an order of magnitude less.

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