From: "IBM Mainframe Assembler List" <ASSEMBLER-LIST@LISTSERV.UGA.EDU>
Sent:Fri, 2 Feb 2018 00:49:57 -0600
Subject:Re: Pascal (was : comparison C vs HLASM)

 > On Feb 1, 2018, at 9:13 PM, Robin Vowels <>
 >> From: "Paul Gilmartin"
 >> Sent: Friday, February 02, 2018 2:16 AM
 >> On 2018-02-01, at 06:55:29, Paul Raulerson wrote:
 >>> It also explains one of the reasons why strings in C are null
terminated. There were two modes of thought back in those days,
‘Pascal’ strings, which have the string size encoded in a single
byte at the start of the string, and ‘C’ strings, which terminate
a string with a NULL.
 >>> Pascal string length was obviously limited by the max value of a
byte ...
 >>> Who made that moronic "single byte" rule!?
 >> The implementer.

 > A few very smart implementors actually. :) 

 >> o It should be two pointers, first byte and last byte + 1.
 > The address of the start of the string and the length are probably

 In machines with 4K of memory or less?

Indeed.  As we have said, substrings require only a pointer (an
and a length (one or two bytes), resulting in considerable saving of

> Well, a PDP-7 had 18bit word lengths, and that 4K was in words.
> I think it was about $70K for a PDP-7 in those days,

The DEUCE, with 384 words of memory, ran ALGOL.
The drum was 8192 words.

> wire wrapped beastie that it was. Engineering changes were made with
wire wrap tools. 

 > And yet, a full multi-user UNIX ran on the thing, with a C compiler
that could compile itself. That’s amazing… 

 >>> o And having the length contiguous meant that substrings
 >>> could not be created without copying.
 >> Indeed.
 >> It's startling how difficult it can be to shift paradigm
 >> beyond "two modes of thought" and invent another.
 >> BTW, those "'Pascal' strings" were not in Wirth's specification
 >> of Pascal; they came later with, e.g. UCSD. 

 > Actually - they were there on ancient old C/PM machines. PIP PIP
and all that. 

 > What actually does amaze me is that anyone would call what those
people did “Moronic”.
> It makes me seriously wonder. 

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