9fans archive / 1999 / 01 / 33 /    prev next

From: Stuart Friedberg stuartf@seq...
Subject: [9fans] time size
Date: Wed, 20 Jan 1999 19:00:20 -0800 (PST)

In article <1E485299309FD211A2100090271E27A4142D04@sym...> you write:
>Hey! Leave off PDP-10s. They had 9 bit chars.

They had any size chars you wanted from 1 to 36, but some char sizes
produced a lot of internal fragmentation.  The most efficient sizes were
 1 (36/word),
 2 (18/word),
 3 (12/word),
 4 ( 9/word),
 5 ( 7/word + 1 bit),
 6 ( 6/word),
 7 ( 5/word + 1 bit),
 8 ( 4/word + 4 bits), 
12 ( 3/word), and
18 ( 2/word),

Nine-bit characters were an especially wasteful size, as you could
only get three per word.  Might as well use 12-bit chars.

The "7-bit char plus 1 bit to indicate a line number" was probably the
most common, although the 6BIT representation was used a lot in the
systems code...

Stu Friedberg (stuartf@seq...)