Subject: Re: NetBSD/pdp10 ?
To: <>
From: David Laight <david@l8s.co.uk>
List: tech-kern
Date: 03/11/2002 23:40:27
On Sat, Mar 09, 2002 at 06:14:20PM -0500, der Mouse wrote:
> > [...], but later they moved to 9 bit ASCII.
> 
> ...isn't ASCII 7 bit by definition?  Or is "9 bit ASCII" an
> abbreviation for "ASCII in the low 7 bits of a 9-bit field"?  (And in
> that case, I'm curious: what did the other 3/4 of the possible values
> mean, do you happen to know?)

Probably all zero.

What about 6 bit ASCII?

The Singer system 10 had 6 bit memory, but for IO it was considered
to be bits 0-4 and 6 of a byte. Bit 5 was generated as the inverse
of bit 6.

The ICL 1900 had 6 bit characters that (largely) match ASCII
0x30..0x3f, 0x20..0x2f, 0x40..0x6f.
(anyone got an Algol 68-R compiler?)

	David

-- 
David Laight: david@l8s.co.uk