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Cool! This expands on the text processing issues: https://www.museumwaalsdorp.nl/en/history/computerhistory-background-information/6400hwac/ https://www.museu

by tpmx 7y ago

Cool! This expands on the text processing issues: https://www.museumwaalsdorp.nl/en/history/computerhistory-background-information/6400hwac/ https://www.museumwaalsdorp.nl/en/history/computerhistory-ba... "There was no byte addressability. If you wanted to store multiple characters in a 60-bit word, you had to shift and mask. Typically, a six-bit character set was used, which meant no lower-case. These systems were meant to be (super)computing engines, not text processors! To signal the end of a text string, e.g. a sentence, two different coding techniques were invented. The so-called 64 character set was the CDC-default. A line end comprised of two (or more) null-“bytes” at the end of a word followed by a full zero word. The 63 character set, quite popular in the Netherlands and the University of Austin, Texas, signalled the line termination by two (or more) null-“bytes” at the end of a 60-bit word. The Michigan State University (MSU) invented a 12-bit character set, which was basically 7-bit ASCII format with five wasted bits per character. Other sites used special shift/unshift characters in a 6-bit character set to achieve upper/lower case."

mark-r 7y ago
I had my own text library where I converted to/from ASCII internally. There was nothing special about the 6 bit boundaries, so you could use any number of bits per character that you wanted until it was time to interact with the rest of the system. By the time I used it they had extended the character set to include lower case by using a special prefix character.
- tpmx 7y ago
  Why were you doing text processing on a "scientific computer" in the first place? :) Sounds like there may be an interesting story there, maybe.
  - mark-r 7y ago
    It was the general student computer at the University of Minnesota, and the uses it were put to were all over the map. Despite being optimized for number crunching it was an amazing general purpose computer. The most interesting architectural feature was that all I/O was relegated to peripheral processors so that the main CPU could run unimpeded.
    - Gibbon1 7y ago
      I think UCLA had a CDC 6600 being used as a time share system. My memory is very hazy though. We used it remotely via 150 baud terminals. On hot days occasionally bits would get scrambled on the way there and back. 10 PRINT "YOUR MOMMA" came back as 10 PRINT "KOUR IOMMA"
  - BadThink6655321 7y ago
    Supercomputers need compilers, et. al. And now I need to go back and revisit the Pascal compiler for those machines...
    - dfox 7y ago
      The toolchain does not have to run on the supercomputer itself. Most supercomputer architectures have self-hosting toolchains there are also supercomputers that do not. Also compiling or even debugging programs directly on the machine is in most cases plain waste of (expensive) computing resources and it is not that one would ever have only the supercomputer and not any other computers (in fact, many traditional supercomputers cannot boot on their own and have to be booted by some kind of frontend computer).
      - tpmx 7y ago
        Did they also have that at launch time(s), back in the 60s/70s?
        B1FF_PSUVM 7y ago
        I believe so, the comp. arch. textbooks were pretty emphatic on the description of the CDC 6600 as "full of peripheral processors", e.g. for I/O and printing, etc. Deliberately, not something tacked on later as an afterthought.
        dfox 7y ago
        I cannot find any information about whether one of the peripheral processors in CDC 6600 (which were full-blown CPUs, not glorified DMA engines as in Cray-1 or System/360) has some kind of system management role. On the other hand Cray-1 needs not one, but two frontend computers to work (one is DG Nova/Eclipse supplied by Cray which actually boots the system and second one has to be provided by customer and is essentially an user interface)
        pinewurst 7y ago
  - dwheeler 7y ago
    I do have a story, I hope it's interesting. The CDC 6600 was used as the student mainframe for George Mason University (GMU) in Northern Virginia in the 1980s. For engineering classes (e.g., electronics engineering) the 6600 was still excellent; it could run simulations far faster than many systems that had been built later, and it was certainly faster at that task than the personal computers of that early time (Apple //es or the original IBM PC). People also used the 6600 for writing text, compiling, etc. The computer was a terrible match for that, but it was fast enough that the mismatch of capabilities still made it useful for the purpose. Oh, and a quick aside: Today's computers are much faster, but much of that speed is taken away by software that's more functional and less efficient. I once shared an IBM PC (4.77MHz) among 16 users. If your computer software is generally efficient, and you're willing to reduce what it does, a single computer can serve a remarkably large number of users. Nobody worried about font selection, for example. So it was with the 6600; it could serve many users, if carefully managed. Now for the story, which I can't confirm but I believe to be true. At the time GMU was a scrappy new local university. It was in a great location (Northern Virginia, which was expanding rapidly). However, although it was a state university, it had little support from the capital (power is divided among counties, and the rural counties easily outvoted Northern Virginia). GMU's president, President Johnson, had much bigger plans for GMU. So Johnson arranged for a hand-me-down supercomputer (the 6600) for nearly nothing. This computer was considered obsolete by then, and it was terrible at text processing. Even so, it was still fast enough to be useful, and more importantly, it was a supercomputer, even though it had been obsoleted. My understanding is that Johnson sold the pitch of "GMU has a supercomputer now" to all the local businesses, asking them to help fund GMU & cooperate in various ways. The local businesses did, greatly so. I suspect most of the businesses knew the "supercomputer" wasn't a current speed champion, and as I far as I know no lies were told. But that wasn't the point. The pitch "we have a supercomputer" was good enough to make it much easier for some people in various businesses to justify (to their cohorts) donating to GMU & working with GMU. Many businesses in Northern Virginia wanted GMU to succeed, because they would greatly benefit long-term with a good university in their backyard... they just needed a good-enough story to win over those who might veto it internally. This "we have a supercomputer" pitch (and other things) worked. Once GMU got "real" money, they invested it, e.g., they upgraded (and kept upgrading) to better equipment. GMU grew quickly into quite a powerhouse; it's now the largest state university in Virginia. One of GMU's distinctives is the huge number of connections it has to local businesses and government organizations. Originally this was because GMU couldn't rely on state funding, but the need to interconnect with local organizations led over time to an emphasis on applying academic knowledge to real-world problems. It's interesting to see how problems + scrappiness can lead to long-term cultures within an organization. Johnson passed away in 2017 ( https://www2.gmu.edu/news/427091 https://www2.gmu.edu/news/427091 ), but his legacy continues.
Someone 7y ago
”The 63 character set, quite popular in the Netherlands and the University of Austin, Texas, signalled the line termination by two (or more) null-“bytes” at the end of a 60-bit word.” So, did Dijkstra invent the null-terminated string? (What else links Austin and the Netherlands in computing at that time?)
- tpmx 7y ago
  > So, did Dijkstra invent the null-terminated string? Seems plausible to me. Or maybe some grad student working with him, and noone really cared who "invented it", since it seemed like such an obvious idea....
- eesmith 7y ago
  I can safely conclude that the content at the site cannot lead us to conclude that Dijkstra invented the nul-terminated string. https://www.museumwaalsdorp.nl/en/history/comphistory/computer-history-the-period-1974-1978/comp742e/ https://www.museumwaalsdorp.nl/en/history/comphistory/comput... says: > A Control Data 6400 system was installed in May 1974 ... > The Laboratory, like all other computer centres in the Netherlands, had opted for the so-called 63 character set. Control Data only tested systems with the 64 character set in America. Unsatisfactory code or code from “new” programmers yielded one or more errors with almost every new release, which we corrected at the TNO Physics Laboratory and made public with a lot of misgivings through the Problem Reporting System mechanism (PSR). Every two weeks a set of microfiches with all complaints and solutions collected worldwide was sent to all computer centres by Control Data. At every release level, it was exciting whether the errors we found were the first to report or that our colleague from the University of Arizona was going to blame That gives a mismatch between "University of Austin, Texas" and "University of Arizona". https://en.wikipedia.org/wiki/Edsger_W._Dijkstra https://en.wikipedia.org/wiki/Edsger_W._Dijkstra says he joined the University of Texas at Austin in 1984. In the 1970s he lived in the Netherlands. https://en.wikipedia.org/wiki/Null-terminated_string https://en.wikipedia.org/wiki/Null-terminated_string says that the PDP-11 in 1970 had NUL-terminated strings ("Null-terminated strings were produced by the .ASCIZ directive of the PDP-11 assembly languages and the ASCIZ directive of the MACRO-10 macro assembly language for the PDP-10.") This was when Dijkstra was at the Eindhoven University of Technology. Therefore, whatever is described at the link cannot be used to conclude that Dijkstra had anything to do with nul-terminated strings.

by tpmx 7y ago

mark-r 7y ago

I had my own text library where I converted to/from ASCII internally. There was nothing special about the 6 bit boundaries, so you could use any number of bits per character that you wanted until it was time to interact with the rest of the system. By the time I used it they had extended the character set to include lower case by using a special prefix character.

tpmx 7y ago
Why were you doing text processing on a "scientific computer" in the first place? :) Sounds like there may be an interesting story there, maybe.
- mark-r 7y ago
  It was the general student computer at the University of Minnesota, and the uses it were put to were all over the map. Despite being optimized for number crunching it was an amazing general purpose computer. The most interesting architectural feature was that all I/O was relegated to peripheral processors so that the main CPU could run unimpeded.
  - Gibbon1 7y ago
    I think UCLA had a CDC 6600 being used as a time share system. My memory is very hazy though. We used it remotely via 150 baud terminals. On hot days occasionally bits would get scrambled on the way there and back. 10 PRINT "YOUR MOMMA" came back as 10 PRINT "KOUR IOMMA"
- BadThink6655321 7y ago
  Supercomputers need compilers, et. al. And now I need to go back and revisit the Pascal compiler for those machines...
  - dfox 7y ago
    The toolchain does not have to run on the supercomputer itself. Most supercomputer architectures have self-hosting toolchains there are also supercomputers that do not. Also compiling or even debugging programs directly on the machine is in most cases plain waste of (expensive) computing resources and it is not that one would ever have only the supercomputer and not any other computers (in fact, many traditional supercomputers cannot boot on their own and have to be booted by some kind of frontend computer).
    - tpmx 7y ago
      Did they also have that at launch time(s), back in the 60s/70s?
      - B1FF_PSUVM 7y ago
        I believe so, the comp. arch. textbooks were pretty emphatic on the description of the CDC 6600 as "full of peripheral processors", e.g. for I/O and printing, etc. Deliberately, not something tacked on later as an afterthought.
        dfox 7y ago
        I cannot find any information about whether one of the peripheral processors in CDC 6600 (which were full-blown CPUs, not glorified DMA engines as in Cray-1 or System/360) has some kind of system management role. On the other hand Cray-1 needs not one, but two frontend computers to work (one is DG Nova/Eclipse supplied by Cray which actually boots the system and second one has to be provided by customer and is essentially an user interface)
        pinewurst 7y ago
- dwheeler 7y ago
  I do have a story, I hope it's interesting. The CDC 6600 was used as the student mainframe for George Mason University (GMU) in Northern Virginia in the 1980s. For engineering classes (e.g., electronics engineering) the 6600 was still excellent; it could run simulations far faster than many systems that had been built later, and it was certainly faster at that task than the personal computers of that early time (Apple //es or the original IBM PC). People also used the 6600 for writing text, compiling, etc. The computer was a terrible match for that, but it was fast enough that the mismatch of capabilities still made it useful for the purpose. Oh, and a quick aside: Today's computers are much faster, but much of that speed is taken away by software that's more functional and less efficient. I once shared an IBM PC (4.77MHz) among 16 users. If your computer software is generally efficient, and you're willing to reduce what it does, a single computer can serve a remarkably large number of users. Nobody worried about font selection, for example. So it was with the 6600; it could serve many users, if carefully managed. Now for the story, which I can't confirm but I believe to be true. At the time GMU was a scrappy new local university. It was in a great location (Northern Virginia, which was expanding rapidly). However, although it was a state university, it had little support from the capital (power is divided among counties, and the rural counties easily outvoted Northern Virginia). GMU's president, President Johnson, had much bigger plans for GMU. So Johnson arranged for a hand-me-down supercomputer (the 6600) for nearly nothing. This computer was considered obsolete by then, and it was terrible at text processing. Even so, it was still fast enough to be useful, and more importantly, it was a supercomputer, even though it had been obsoleted. My understanding is that Johnson sold the pitch of "GMU has a supercomputer now" to all the local businesses, asking them to help fund GMU & cooperate in various ways. The local businesses did, greatly so. I suspect most of the businesses knew the "supercomputer" wasn't a current speed champion, and as I far as I know no lies were told. But that wasn't the point. The pitch "we have a supercomputer" was good enough to make it much easier for some people in various businesses to justify (to their cohorts) donating to GMU & working with GMU. Many businesses in Northern Virginia wanted GMU to succeed, because they would greatly benefit long-term with a good university in their backyard... they just needed a good-enough story to win over those who might veto it internally. This "we have a supercomputer" pitch (and other things) worked. Once GMU got "real" money, they invested it, e.g., they upgraded (and kept upgrading) to better equipment. GMU grew quickly into quite a powerhouse; it's now the largest state university in Virginia. One of GMU's distinctives is the huge number of connections it has to local businesses and government organizations. Originally this was because GMU couldn't rely on state funding, but the need to interconnect with local organizations led over time to an emphasis on applying academic knowledge to real-world problems. It's interesting to see how problems + scrappiness can lead to long-term cultures within an organization. Johnson passed away in 2017 ( https://www2.gmu.edu/news/427091 https://www2.gmu.edu/news/427091 ), but his legacy continues.

Someone 7y ago

”The 63 character set, quite popular in the Netherlands and the University of Austin, Texas, signalled the line termination by two (or more) null-“bytes” at the end of a 60-bit word.” So, did Dijkstra invent the null-terminated string? (What else links Austin and the Netherlands in computing at that time?)

tpmx 7y ago
> So, did Dijkstra invent the null-terminated string? Seems plausible to me. Or maybe some grad student working with him, and noone really cared who "invented it", since it seemed like such an obvious idea....
eesmith 7y ago
I can safely conclude that the content at the site cannot lead us to conclude that Dijkstra invented the nul-terminated string. https://www.museumwaalsdorp.nl/en/history/comphistory/computer-history-the-period-1974-1978/comp742e/ https://www.museumwaalsdorp.nl/en/history/comphistory/comput... says: > A Control Data 6400 system was installed in May 1974 ... > The Laboratory, like all other computer centres in the Netherlands, had opted for the so-called 63 character set. Control Data only tested systems with the 64 character set in America. Unsatisfactory code or code from “new” programmers yielded one or more errors with almost every new release, which we corrected at the TNO Physics Laboratory and made public with a lot of misgivings through the Problem Reporting System mechanism (PSR). Every two weeks a set of microfiches with all complaints and solutions collected worldwide was sent to all computer centres by Control Data. At every release level, it was exciting whether the errors we found were the first to report or that our colleague from the University of Arizona was going to blame That gives a mismatch between "University of Austin, Texas" and "University of Arizona". https://en.wikipedia.org/wiki/Edsger_W._Dijkstra https://en.wikipedia.org/wiki/Edsger_W._Dijkstra says he joined the University of Texas at Austin in 1984. In the 1970s he lived in the Netherlands. https://en.wikipedia.org/wiki/Null-terminated_string https://en.wikipedia.org/wiki/Null-terminated_string says that the PDP-11 in 1970 had NUL-terminated strings ("Null-terminated strings were produced by the .ASCIZ directive of the PDP-11 assembly languages and the ASCIZ directive of the MACRO-10 macro assembly language for the PDP-10.") This was when Dijkstra was at the Eindhoven University of Technology. Therefore, whatever is described at the link cannot be used to conclude that Dijkstra had anything to do with nul-terminated strings.