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The origin and unexpected evolution of the word "mainframe"

The origin and unexpected evolution of the word "mainframe"

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·February 1, 2025
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tommiegannert

> Based on my research, the earliest computer to use the term "main frame" was the IBM 701 computer (1952)

> This shows that by 1962, "main frame" had semantically shifted to a new word, "mainframe."

> IBM started using "mainframe" as a marketing term in the mid-1980s.

I must conclude it takes the competition 10 years to catch up to IBM, and IBM about 20 years to realize they have competition. Setting a countdown timer for IBM to launch an LLM in 2040.

Thanks for researching and writing this up. It's a brilliant read!

kens

Author here. Anyone have interesting mainframe stories?

ggm

A rumour from my mainframe days was that Digital Equipment hired lacemakers from france to show people how they did it. This was wiring up the core memory planes for the Dec-10 (I have one, a folded 3 part card) which just barely squeezes into the mainframe class.

The guy who told me this was the Australian engineer sent over to help make the machine to bring back for UQ. He parked in the quiet side of the Maynard factory, not realising why the other drivers avoided it. Then his car got caught in a snowdrift.

A prior engineer told me about the UUO wire wrap feature on the instruction set backplane: you were allowed to write your own higher level ALU "macros" in the instruction space by wiring patches in this backplane. Dec 10 had a 5 element complex instruction model. Goodness knows what people did in there but it had a BCD arithmetic model for the six bit data (36 bit word so 6 bytes of six bits in BCD mode)

A guy from Latrobe uni told me for their Burroughs, you edited the kernel inside a permanently resident Emacs like editor which did recompile on exit and threw you back in on a bad compile. So it was "safe to run" when it decided your edits were legal.

We tore down our IBM 3030 before junking it to use the room for a secondhand Cray 1. We kept so many of the water cooled chip pads (6" square aluminium bonded grids of chips, for the water cooler pad. About 64 chips per pad) the recycler reduced his bid price because of all the gold we hoarded back.

The Cray needed two regenerator units to convert Australian 220v to 110v for some things, and 400hz frequency for other bits (this high voltage ac frequency was some trick they used doing power distribution across the main CPU backplane) and we blew one up spectacularly closing a breaker badly. I've never seen a field engineer leap back so fast. Turned out reusing the IBM raised floor for a Cray didn't save us money: we'd assumed the floor bed for liquid cooled computers was the same; not so - Cray used a different bend radius for flourinert. The flourinert recycling tank was clear plastic, we named the Cray "yabby" and hung a plastic lobster in it. This tank literally had a float valve like a toilet cistern.

When the Cray was scrapped one engineer kept the round tower "loving seat" module as a wardrobe for a while. The only CPU cabinet I've ever seen which came from the factory with custom cushions.