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From: bd@zyx.UUCP (Bjorn Danielsson)
Newsgroups: comp.arch
Subject: Re: machine word sizes
Message-ID: <1241@zyx.UUCP>
Date: Mon, 27-Jul-87 12:29:02 EDT
Article-I.D.: zyx.1241
Posted: Mon Jul 27 12:29:02 1987
Date-Received: Thu, 30-Jul-87 06:52:25 EDT
References: <2807@phri.UUCP> <565@saturn.ucsc.edu> <1184@k.cs.cmu.edu> <2817@phri.UUCP>
Reply-To: bd@zyx.UUCP (Bjorn Danielsson)
Organization: ZYX Sweden AB, Stockholm
Lines: 15

In article <2817@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
>	DEC didn't let the migration to 16-bit words sway them from 6+3
>filenames.  Au contrare, they simply invented the rad-50 character code so
>you could pack 3 characters into 16 bits.  You got 26 upper-case letters,
>10 digits, and 14 random pieces of punctuation.  Blech!  I don't remember
>the exact details of rad-50 to ascii conversion, but I seem to recall it
>being about as complex as 4.3's namei :-)

Actually, the radix-50 code has only 40 characters. The figure "50" is an
octal number. 40*40*40 = 64000, which fits nicely into 16 bits. Or you can
pack 6 characters into 32 bits, which is what they did on the PDP-10, leaving
4 extra bits for other uses (flag bits, etc).
The character set was " _.$ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".
-- 
Bjorn Danielsson, ZYX, +46 8 653205, ...mcvax!enea!zyx!bd