Re: smashing down callsigns into 32 bits
- To: firstname.lastname@example.org
- Subject: Re: smashing down callsigns into 32 bits
- From: Fred Goldstein <email@example.com>
- Date: Fri, 2 Dec 94 11:49:28 EST
- Cc: firstname.lastname@example.org, TCP-Group@ucsd.edu
- In-reply-to: <199412012048.AA09177@foxtrot.rahul.net>
- Mail-system-version: <BBN/MacEMail_v1.5@BBN.COM>
>It turns out to be easy to map 6-character identifiers (including callsigns)
>into 32 bits uniquely.
>Those of us who are "old timers" can remember a DEC funny format called
>"Radix 40". It coded 3 characters into 16 bits. (You see, 40^3 = 64,000)
>The character set had, as you might suspect, 40 charcters: 0-9, A-Z, space
>and 3 punctuation marks. Have you ever wondered why on those old DEC minis
>you had filenames like FOOBAR.BAZ? Now you know: filenames fit into 3
Actually, it was "Radix-50", not -40. I think it's documented in
the RT-11 manual set. It's probaby deep in my attic.
The original poster's fallacy, of course, was in forgetting how to
determine permutations. The proper value of a field AA9AAA is
26^5 * 10, noting of course other formats too so more likley 27^5
and when you add non-US signs like C21 and 4N7 it gets a bit bigger...
Fred R. Goldstein email@example.com
Bolt Beranek & Newman Inc. Cambridge MA USA +1 617 873 3850