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

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 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.

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-techno...

See also, for example, "what makes the 1401 so interesting?" 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".

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

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