1 Oct
2004
1 Oct
'04
12:47 a.m.
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