[TUHS] origin of null-terminated strings
Dan Halbert
halbert at halwitz.org
Sat Dec 17 07:20:59 AEST 2022
On 12/16/22 16:02, Warner Losh wrote:
> On Fri, Dec 16, 2022, 1:12 PM Dave Horsfall <dave at horsfall.org> wrote:
>
> On Fri, 16 Dec 2022, Dr Iain Maoileoin wrote:
>
> > I remember running into a .asciz directive n the 70s
> “somewhere”. It was
> > an assembler directive in one of the RT11 systems??? or perhaps
> the unix
> > bootstrap and/or “.s” files - when I get some time I will go
> read some
> > old code/manuals.
>
> MACRO-11 on RSX-11D seems to ring a bell...
>
>
> I first encountered it on RSTS/E 6C in the MACRO-11 it had... But the
> v6 macro assembler from DEC via Harvard that eventually wound up in
> 2BSD is older and dates to 1977 or so.
>
> Warner
The PDP-10 manual I spoke of is from 1971, and there were older
editions. For the PDP-7, this manual from 1965,
http://www.bitsavers.org/pdf/dec/pdp7/PDP-7_AsmMan.pdf, printed pages
38-40, does not mention "ASCIZ" specifically, but talks about assembler
directives "TELETYPE" and "ANALEX" that add a "termination code" of 00
octal, for characters.
DEC also used SIXBIT, a truncated ASCII code that had printing
characters but no control characters, so no newline, etc. In that
scheme, 00 octal was SPACE. Table here:
https://en.wikipedia.org/wiki/Six-bit_character_code#Examples_of_six-bit_ASCII_variants.
Dan H
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