6 ms·

I used and programmed the 6600, including in assembly language. They were incredibly fast for the time at numerical calculation. I used them for electronics sim

I used and programmed the 6600, including in assembly language. They were incredibly fast for the time at numerical calculation. I used them for electronics simulations in SPICE, and they were great for that. However, they had 60 bit words and no way to address data directly within a word. By convention, characters were six bits long, stuffed in 10 characters to a word. So while this machine was incredibly fast for its time for numerical calculation, it was painful to do text manipulation. You had to pack and shift characters into words, and unshift and unpack. You could do interesting things with great cleverness, but it took a lot of work to do simple things. Thanks for the trip down memory lane.

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).
        7y ago
- 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.
pvg 7y ago
it was painful to do text manipulation Another way to think of it is that it was fully emoji-and-variant-selector-ready way ahead of its time.

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).
      - 7y ago
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.

pvg 7y ago

it was painful to do text manipulation Another way to think of it is that it was fully emoji-and-variant-selector-ready way ahead of its time.