Another (mid-late) data point may be the original NeXT brochure[1], which claims the NeXT to be "a mainframe on two chips". It provides a definition along the lines of a throughput oriented architecture and peripheral channels (in analogy to the NeXT's two DSP chip) and, while doing so, also marries the concepts of physical size and architecture (there's also some romanticism around uncompromised designs and "ruthless efficiency" involved):
> The NeXT Computer acknowledges that throughput is absolutely key to performance. For that reason, we chose not to use the architecture of any existing desktop computer. The desired performance could be found only in a computer of a different class: the mainframe.
> Having long shed any self-consciousness over such mundane matters as size and expense, mainframes easily dwarf desktop computers in the measure of
throughput.
> This is accomplished by a different kind of architecture. Rather than require the attention of the main processor for every task, the mainframe has a legion of separate Input/Output processors, each with a direct channel to memory It's a scheme that works with ruthless efficiency.
There's also the Intel iAPX 432 "micro-mainframe" processor (1981) on two chips. (This was supposed to be Intel's flagship processor, but it was a disaster and the 8086 took over instead. The NYT called it "one of the great disaster stories of modern computing".) I think that microprocessor manufacturers had mainframe envy in the 1980s.
> 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!
I can kind of see why this should have been. The 1401, which was really intended as a replacement for IBM's punchcard appliances, was widely known as IBM's small mainframe. On the other hand, there are the 701, things like the 7030 (Stretch), and then the ranges of the S/360 and S/370. – Considering this rather inconceivable wide class of machines, stepping in and deciding, what's a mainframe and what's not, is a losing game, from a marketing perspective. So better keep silent and reap the fruits…
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.
I heard a story of Seymour Cray doing a demo of one of the machines and it turned out there was a bug in some hardware procedure. While the customers were at lunch, Seymour opened up the machine, redid the wire wrap and had the bug fixed when they returned. (Note that many details are likely inaccurate as this is a 35-year-old memory of a second-hand story.)
I have searched once for the origin of the term "Central Processing Unit".
In his report, John von Neumann had used the terms "central arithmetical part (CA)" and "central control part (CC)". He had not used any term for the combination of these 2 parts.
The first reference to CPU that I could find is the IBM 704 manual of operation from 1954, which says: “The central processing unit accomplishes all arithmetic and control functions.”, i.e. it clearly defines CPU as the combination of the 2 parts described by von Neumann.
In IBM 704, the CPU was contained in a single cabinet, while in many earlier computers multiple cabinets were used just for what is now named CPU. In IBM 704, not only the peripherals were in separate cabinets, but also the main memory (with magnetic cores) was in separate cabinets. So the CPU cabinet contained nothing else.
The term "processor" has appeared later at some IBM competitors, who used terms like "central processor" or "data processor" instead of the "central processing unit" used by IBM.
Burroughs might have used "processor" for the first time, in 1957, but I have not seen the original document. Besides Burroughs, "processor" was preferred by Honeywell and Univac.
The first use of "multiprocessing" and "multiprocessor" that I have seen was in 1961, e.g. in this definition by Burroughs: "Multiprocessing is defined here as the sharing of a common memory and all peripheral equipment by two or more processor units."
While "multi-tasking" was coined only in 1966-09 (after IBM PL/I had chosen in 1964-12 the name "task" for what others called "process"), previously the same concept was named "multiprogramming", which was already used in 1959, when describing IBM Stretch. ("multitasking" was an improved term, because you can have multiple tasks executing the same program, while "multiprogramming" incorrectly suggested that the existence of multiple programs is necessary)
You've done a lot of interesting historical research there! I wanted to get into a discussion of "central processing unit", but decided my article was long enough already :-) The term "central processing unit" is unusual since it is a seven-syllable term for a fundamental idea. Even "CPU" is a mouthful. I think that the "central" part is in opposition to systems such as ENIAC or the Harvard Mark I, where processing is spread out through the system through accumulators that each perform addition. Centralizing the processing was an important innovation by von Neumann.
We will never get rid of the "von Neumann bottleneck", except for a relatively small number of niche applications.
The bottleneck consists in the fact that instead of having a huge number of specialized automata that perform everything that must be done to execute a useful application you have just an universal automaton together with a big memory, where the universal automaton can perform anything when given an appropriate program.
The use of a shared automaton prevents many actions to be done concurrently, but it also provides a huge economy of logical circuits.
The "von Neumann bottleneck" is alleviated by implementing in a computer as many processor cores as possible at a given technological level, each with its own non-shared cache memory.
However removing completely the concept of programmable processor with separate memory would multiply the amount of logic circuits too much for any imaginable technology.
The idea of mixing computational circuits with the memory cells is feasible only for restricted well defined applications, e.g. perhaps for something like ML inference, but not for general-purpose applications.
My mom was a programmer back in the 1950s. First thing in the morning, she would run a memory test. If it failed, she would slide out the failing tray of memory (100 words by 36 bits, and tubes), hand it off to a tech to fix, slide in a fresh tray, and proceed.
She had one CPU she worked on where you could change its instruction set by moving some patch cords.
A tax agency unified all its data from different agencies via X.25 and satellite connections. However, the process was expensive and slower than expected because the files were uncompressed and stored as basic plain-text ASCII/EBCDIC files.
One obvious solution to this problem was to buy an Ethernet network device for the mainframe (which used Token Ring), but that was yet another very expensive IBM product. With that device, we could have simply compressed and uncompressed the files on any standard PC before transferring them to/from the mainframe.
Another obvious solution was to use C to compile a basic compression and decompression tool. However, C wasn’t available—buying it would have been expensive as well!
So, we developed the compression utility twice (for performance comparisons), using COBOL and REXX. These turned out to be two amusing projects, as we had to handle bits in COBOL, a language never intended for this purpose.
The capture of all thought by IBM at these palaces was nuts.
Circa 2002 I’m a Unix admin at a government agency. Unix is a nascent platform previously only used for terminal services. Mostly AIX and HPUX, with some Digital stuff as well. I created a ruckus when I installed OpenSSH on a server (Telnet was standard). The IBM CE/spy ratted me out to the division director, who summoned me for an ass chewing.
He turned out to be a good guy and listened to and ultimately agreed with my concerns. (He was surprised, as mainframe Telnet has encryption) Except one. “Son, we don’t use freeware around here. We’ll buy an SSH solution for your team. Sit tight.”
I figured they’d buy the SSH Communications software. Turned out we got IBMSSH, for the low price of $950/cpu for a shared source license.
I go about getting the bits and install the software… and the CLI is very familiar. I grab the source tarball and it turns out this product I never heard of was developed by substituting the word “Open” with “IBM”. To the point that the man page had a sentence that read “IBM a connection”.
> C wasn’t available—buying it would have been expensive as well!
On the subject of expensive mainframe software, I got to do the spit take once of "you are paying how much for a lousy ftp client? per month!" I think it was around $500 per month.
The youngs have no idea. You used to have to pay for development tools. In high school, I would hand-assemble my 6502 assembler programs by writing them out longhand on graph paper, fill in the hex in the left columns than type in the hex in the Apple monitor to get the program running. Heaven forbid there was anything wrong with the code, the hand-assembling or the keyboarding, but I couldn’t afford one of the paid assemblers (in retrospect, I should have written one in AppleSoft, but hindsight is 20/20, and I don’t know that I was smart enough then to write an assembler anyway). Spending $500–1000 for a compiler in the 90s was typical. Now the kids whine about paying the relatively cheap fee for things like JetBrain IDEs.
Back about roughly 1978 to 1982, I wrote and sold a 6800/6809 disassembler ("Dynamite Disassembler") for I think $200 a copy. Sold enough copies to pay for computer equipment during my college days. I think we reduced the price to $100 or maybe $150 when the TRS-80 Color Computer came out with a 6809 powering it.
$200 back in 1980 is about $800 today. Amazing to think anyone would spend that much for a fairly simple tool.
We were running Oregon Pascal on a PDP/11-44 (later upgraded to a VAX 11/780) that cost thousands. To have access to Pascal for $49 was too good to be true. Kept thinking it had to be deficient somehow, but it wasn't.
The paradigm shift was underway right in front of us.
My CS 101 class in 1989 was all in Pascal and had to be entered via a IBM terminal and ran as a batch job on our school mainframe. There was no interactive feedback and you had to hike across campus to a basement of a building that had an enormous chain printer to get your greenbar paper output of your run to see if it 1) compiled and 2) output the right thing that the autoscorer checked when you flagged your assignment as complete.
I was lucky in that I had a Tandy 1000SX in my dorm room and I had Turbo Pascal (bought using an educational discount at the school bookstore). A hidden feature of Turbo Pascal was that it supported multiple comment delimiters, including the comment delimiters used by IBM Pascal (the assignments were also graded on comment quality). I was able to do all my class work locally, using interactive debugging, and thanks to a guy I met while working at a local computer shop that was the student IBM rep I got a file uploader and the phone number of hidden 2400 baud that it used so I could directly upload my code and then dial into the interactive terminal number and submit it.
I sort of felt bad for all the other kids in the class for the write/submit/walk/debug loop they endured, but not really.
> Another obvious solution was to use C to compile a basic compression and decompression tool. However, C wasn’t available—buying it would have been expensive as well!
I would have thought in the (IBM) mainframe world, PL/I (or PL/S) would have been the obvious choice.
Ken, surely frames significantly pre-date the computer? They were used in telephone exchanges. The Colossus reproduction at Bletchley is constructed from frames.
I discuss this a bit in footnote 1. Thousands of things were built on frames before computers, of course. However, IBM both built computers from semi-portable cabinets built around metal frames and also referred to the computer's units as "frames", including the "main frame".
Telephone systems used main distribution frames, but these are unrelated. First, they look nothing like a computer mainframe, being a large rack with cable connections. Second, there isn't a path from the telephony systems to the computer mainframes; if the first mainframes were developed at Bell Labs, for instance, it would be plausible.
Telephone switches introduced the idea of frames. They were the first systems to have enough components to require modular organization. Western Electric tended to use 24 inch spacing.
19 inch racks seem to come from railroad interlocking and may have been introduced by Union Switch and Signal, founded by Westinghouse in 1881, and still around, as a unit of Ansaldo.
Fascinating. I read Byte Magazine, among others, back in the late 70's and 80's and I don't recall ever running across "mainframe" as a synonym for "CPU" or seeing it applied to mini- and micro-computers. I won't dispute the OP's citations from Byte, obviously, but I have to think it wasn't that common.
The term goes back to a time when each component of a data processing system (cpu, storage devices, printers, card readers/punch card machines/teletype, and later monitors and communication devices were all separately housed in structure or frames. The central or main component was the cpu ie. the main frame. Note: IBM was required per consent decree unbundle ie. to sell these devices as separately priced products not as an all or nothing system.
Loosely related to unexpected word origins, I didn't know until recently that when "gaslighting" someone, you're using an expression tied to literal gaslights from a 1944 movie. I'm likely late to the party on learning this origin.
Yes; I watched the movie "Gaslight" recently, and the meaning that everyone uses has drifted pretty far from the movie's meaning. But it's probably hopeless to resist a meaning when it becomes trendy.
Another (mid-late) data point may be the original NeXT brochure[1], which claims the NeXT to be "a mainframe on two chips". It provides a definition along the lines of a throughput oriented architecture and peripheral channels (in analogy to the NeXT's two DSP chip) and, while doing so, also marries the concepts of physical size and architecture (there's also some romanticism around uncompromised designs and "ruthless efficiency" involved):
> The NeXT Computer acknowledges that throughput is absolutely key to performance. For that reason, we chose not to use the architecture of any existing desktop computer. The desired performance could be found only in a computer of a different class: the mainframe.
> Having long shed any self-consciousness over such mundane matters as size and expense, mainframes easily dwarf desktop computers in the measure of throughput.
> This is accomplished by a different kind of architecture. Rather than require the attention of the main processor for every task, the mainframe has a legion of separate Input/Output processors, each with a direct channel to memory It's a scheme that works with ruthless efficiency.
[1] https://lastin.dti.supsi.ch/VET/sys/NeXT/N1000/NeXTcube_Broc...