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From: kaufman@Neon.Stanford.EDU (Marc T. Kaufman)
Newsgroups: comp.sys.mac.comm
Subject: Re: where did 132 (characters) come from?
Message-ID: <1990Dec22.225426.20762@Neon.Stanford.EDU>
Date: 22 Dec 90 22:54:26 GMT
References: <4208@mindlink.UUCP>
Organization: Computer Science Department, Stanford University
Lines: 25

In article <4208@mindlink.UUCP> a544@mindlink.UUCP (Rick McCormack) writes:
>John DeRosa, uunet!motcid!derosaj, in an article writes:

-> BTW, where did 132 come from?  Looks like a number that
-> someone pulled from mid-air like 5280 feet in a mile or 2.5
-> inches in a British Nail (gawd, I love the CRC).

.in text based systems, using mono-spaced text, and the standard (Ha-ha) eight
.inch wide paper of the teletype, there were 80 characters in a standard
.10-pitch line; 96 in a 12-pitch line.  (these were known as pica and elite,
.respectively.) Compressed type was printed at 16.5 characters per inch.
.Voila!!

When 132 column printout originated, there were no "compressed" teletypes.
132 characters, at 10 characters per inch (pica spacing), is just under
13.2" wide.  This is (almost) the most printing that you can get on 14" wide
tractor-feed paper... of the kind used in the IBM 1403 printer.  Older, drum
based 402 printers, could only print 120 characters across.  132 is also
a multiple of 12, which just happens to be the bit-width of an IBM 704x or
709x data channel (this is useful for printers that are loaded by row, rather
than by column).  132 is also 6 x 22.  Each 7090 word held 6 characters (6 bits
per character).  132 character screen displays were invented specifically to
be able to view an entire print line at once.

Marc Kaufman (kaufman@Neon.stanford.edu)