5 ms·

Author here. Anyone have interesting mainframe stories?

by kens 2y ago

ggm 2y ago
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.
- dhosek 2y ago
  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.)
wslh 2y ago
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.
- somat 2y ago
  > 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. Man open source software really has us spoiled.
  - dhosek 2y ago
    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.
    - philiplu 2y ago
      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.
raldi 2y ago
Does this guy deserve a call-out? https://en.wikipedia.org/wiki/Mainframe_(G.I._Joe) https://en.wikipedia.org/wiki/Mainframe_(G.I._Joe)
AnimalMuppet 2y ago
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.
adrian_b 2y ago
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)
- d1sxeyes 2y ago
  And of course back when everyone had desktop towers, “the CPU” was everything except the monitor and the peripherals.
- kens 2y ago
  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.
dwheeler 2y ago
I want to say "thank you" for the careful research examining multiple original sources from a variety of viewpoints.

Author here. Anyone have interesting mainframe stories?

by kens 2y ago

Author here. Anyone have interesting mainframe stories?

ggm 2y ago

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.

dhosek 2y ago
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.)

wslh 2y ago

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.

somat 2y ago
> 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. Man open source software really has us spoiled.
- dhosek 2y ago
  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.
  - philiplu 2y ago
    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.

raldi 2y ago

Does this guy deserve a call-out? https://en.wikipedia.org/wiki/Mainframe_(G.I._Joe) https://en.wikipedia.org/wiki/Mainframe_(G.I._Joe)

AnimalMuppet 2y ago

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.

adrian_b 2y ago

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)

d1sxeyes 2y ago
And of course back when everyone had desktop towers, “the CPU” was everything except the monitor and the peripherals.
kens 2y ago
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.

dwheeler 2y ago

I want to say "thank you" for the careful research examining multiple original sources from a variety of viewpoints.