On Tue, Aug 18, 2009 at 01:45:27PM -0400, Karl Vogel wrote: > >> On Mon, 17 Aug 2009 17:23:29 -0700, > >> Walt Pawley <w...@wump.org> said: > > W> As speculation on my part, perhaps the six character limitation is less > W> a software issue than an early architecture issue - DEC's PDP-6/10 > W> design used 36-bit words and packed six characters (clearly from a > W> limited subset of the then current ASCII) per word, making simple > W> searches very effective through symbol tables with a simple word level > W> compare loop. > > I'll second that. My first job for Uncle Sugar was on a DEC 10/55 > for the Air Force, and 36-bit words were a fact of life. There were > lots of programs around for conversion to/from 32-bit words, just so > we could talk to everybody else on Earth.
CDC (Control Data) mainframe machines used 6 bit characters. I believe the 3600 series had 36 bit words. The 6000 series (6400, 6500, etc, plus 170/750) used 60 bit words but still used 6 bit characters. So, everything was all upper case. It had 12 bit 'peripheral processors' which tended the 60 bit main processor[s] so later started to use 12 bit characters or sometimes 8 in 12 to allow for upper/lower case. That was a Seymour Cray thing. He designed their early mainframes before he bolted to make his own companies (so he wouldn't have to conform to corporate control). Later CDC came out with their 180 series that used 64 bit words and 8 bit bytes. It was kind of a nice system but it was too late for them. The world was turning to clusters of cheap CPU chips running UNIX instead of massive mainframes running proprietary OSen and CDC didn't jump on that bandwagon soon or strongly or cheaply enough. Anyway, in those earliest of days, 6 bits was the economical character set. But it was an obstacle to upper/lower case characters without using some shift code. IBM and DEC started doing 8 bit bytes - I don't know just when - and that allowed eash use of upper/lower characters and so quickly determined the standard character size for a long time. Now that 8 bit byte is a thorn in the side of those who want to create and universalize a character set that is international. ////jerry > > -- > Karl Vogel I don't speak for the USAF or my company > > Men are liars. We'll lie about lying if we have to. I'm an > algebra liar. I figure two good lies make a positive. --Tim Allen > _______________________________________________ > email@example.com mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org" _______________________________________________ firstname.lastname@example.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"