Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rutgers!att!ulysses!andante!alice!dmr
From: dmr@alice.UUCP
Newsgroups: comp.arch
Subject: Re: String lengths
Message-ID: <8882@alice.UUCP>
Date: 7 Feb 89 07:57:35 GMT
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 24

Robert Firth justifiably corrects my misstatement about
BCPL strings; they were indeed counted.  I evidently edited
my memory.

Perhaps he or someone else can discuss authoritatively how they
fitted into the language and (to recall the original topic) how string
instructions might help in processing.  More nearly correct
memory--which applies only to 20-year-old implementations
on the IBM 7090 and GE 635/645--says that strings existed
in two forms: a one-byte count followed by the characters
of the string, and an expanded form in which the count
and the characters were blown out into words.

In these implementations, bytes were 9 bits, and so the compact
representation limited strings to length 511.  On the
other hand, the blown-out form occupied lots of space and
wasn't suitable for transferring directly to text files.
Originally, I believe, there were no operators for accessing
individual characters in a compact string, though they were
added later.

	Dennis Ritchie
	att!research!dmr
	dmr@research.att.com