From mboxrd@z Thu Jan  1 00:00:00 1970
From: norman@nose.cs.utoronto.ca (Norman Wilson)
Date: Thu, 30 Sep 2004 20:47:22 -0400
Subject: [TUHS] 6-bit, 7-bit and 9-bit byte UNIXes
Message-ID: <20041001005644.2B3F7373@minnie.tuhs.org>

The very first UNIX ran on the PDP-7, which had 18-bit words.

I happen to have the assembly-language source code to parts
of that system.  Many programs contain error-handling code
that does something like this:

	lac d1
	sys write; 1f; 1
	jmp somewhere

1:	077012

	...

d1:	1

Evidently the system thought in words in those days
(the second argument to sys write is presumably a word
count), but the single word written is a strong clue
that 9-bit bytes were used, and that a certain concise
error message that people love to complain about was
there from the beginning (and why not?).

Norman Wilson
Toronto ON