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.

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...

• chihuahua

  today at 7:46 PM

  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"?

• nick__m

  today at 5:22 PM

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

  • kens

    today at 5:25 PM

    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."

    • jasomill

      today at 8:26 PM

      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.

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.

• kens

  today at 5:36 PM

  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?

  • rootusrootus

    today at 5:49 PM

    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.

    • kens

      today at 5:55 PM

      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.