4 ms·

Qui-binary arithmetic: how a 1960s IBM mainframe does math

76 points by JoachimS 11y ago

NelsonMinar 11y ago
Shirriff has written several posts about the IBM 1401: his notes on SMS logic cards are particuarly interesting. Sort of like a services architecture, only instead of "real time database" as a component it's "three-way OR". http://www.righto.com/2015/03/a-database-of-sms-cards-technology.html http://www.righto.com/2015/03/a-database-of-sms-cards-techno...
russell 11y ago
I have fond memories of the 1401, although I never programmed one. In the mid 60s I worked for the Harvard Computer Center. We had a 1401 whose sole job was a tape to print server for the 7094. It had attached a 1403 printer, a screaming behemoth (literally) that could print 600 lines per minute. http://www.columbia.edu/cu/computinghistory/1403.html http://www.columbia.edu/cu/computinghistory/1403.html compares the sound of a 1403 to a jet plane, an old jet, mind you, now one of those whisper quite modern ones. There are stories of people writing music to be played on a 1403, maybe even true. Another feature was the 1301 disk drive, the size of two refrigerators, with an astounding 28 megabytes of storage,whirling away at 1800 rpm. For a mere $2000 a month you could have your own. Computers tha one person can carry are for wimps.
- Perixoog 11y ago
  1403 music - http://wayback.archive.org/web/20070203125146/http://www.computerhistory.org/exhibits/highlights/ http://wayback.archive.org/web/20070203125146/http://www.com...
  - omnibrain 11y ago
    I expected the link to be this: https://www.youtube.com/watch?v=_o_WF7N73Kw https://www.youtube.com/watch?v=_o_WF7N73Kw
tempodox 11y ago
Shouldn't it rather be “bi-quinary” instead of “qui-binary”?
- kens 11y ago
  As the first footnote explains, bi-quinary numbers are what an abacus uses: one part is 0,1,2,3 or 4 and the other is 0 or 5. Qui-binary numbers are the opposite: one part is 0,2,4,6 or 8 and the other part is 0 or 1.
theoh 11y ago
See also, for example, "what makes the 1401 so interesting?" http://www.zyvra.org/lafarr/ibm1401.htm http://www.zyvra.org/lafarr/ibm1401.htm It's a shame there's no way to gather HN posts about the 1401 with a tag "ibm1401".
rdc12 11y ago
Quite neat to be able to see, the logic on the board instead of being hidden inside mass blob of transistors.

76 points by JoachimS 11y ago

Shirriff has written several posts about the IBM 1401: his notes on SMS logic cards are particuarly interesting. Sort of like a services architecture, only instead of "real time database" as a component it's "three-way OR". http://www.righto.com/2015/03/a-database-of-sms-cards-technology.html http://www.righto.com/2015/03/a-database-of-sms-cards-techno...

russell 11y ago

I have fond memories of the 1401, although I never programmed one. In the mid 60s I worked for the Harvard Computer Center. We had a 1401 whose sole job was a tape to print server for the 7094. It had attached a 1403 printer, a screaming behemoth (literally) that could print 600 lines per minute. http://www.columbia.edu/cu/computinghistory/1403.html http://www.columbia.edu/cu/computinghistory/1403.html compares the sound of a 1403 to a jet plane, an old jet, mind you, now one of those whisper quite modern ones. There are stories of people writing music to be played on a 1403, maybe even true. Another feature was the 1301 disk drive, the size of two refrigerators, with an astounding 28 megabytes of storage,whirling away at 1800 rpm. For a mere $2000 a month you could have your own. Computers tha one person can carry are for wimps.

Perixoog 11y ago
1403 music - http://wayback.archive.org/web/20070203125146/http://www.computerhistory.org/exhibits/highlights/ http://wayback.archive.org/web/20070203125146/http://www.com...
- omnibrain 11y ago
  I expected the link to be this: https://www.youtube.com/watch?v=_o_WF7N73Kw https://www.youtube.com/watch?v=_o_WF7N73Kw

tempodox 11y ago

Shouldn't it rather be “bi-quinary” instead of “qui-binary”?

kens 11y ago
As the first footnote explains, bi-quinary numbers are what an abacus uses: one part is 0,1,2,3 or 4 and the other is 0 or 5. Qui-binary numbers are the opposite: one part is 0,2,4,6 or 8 and the other part is 0 or 1.

theoh 11y ago

See also, for example, "what makes the 1401 so interesting?" http://www.zyvra.org/lafarr/ibm1401.htm http://www.zyvra.org/lafarr/ibm1401.htm It's a shame there's no way to gather HN posts about the 1401 with a tag "ibm1401".

rdc12 11y ago

Quite neat to be able to see, the logic on the board instead of being hidden inside mass blob of transistors.