[TUHS] PDP-10 UNIX?
krewat at kilonet.net
Tue Sep 19 02:42:02 AEST 2017
The MACRO-10 assembler used a keyword ASCIIZ to store that
7-bit/1-bit-wasted ASCII format.
MOVEI 0,[ASCIIZ /Hello there
for example. It was the defacto standard for null-terminated ASCII strings.
When I later moved to C on 8/16-bit computers, I remember thinking
"what's with this signed 8-bit char thing?" ;)
There was also SIXBIT - almost everything ASCII had, but only upper
case. The filesystem used that for filenames and extensions, and it was
used in a few other areas. So any library calls like open() would have
had to convert the ASCII filename to SIXBIT before doing any monitor calls.
On 9/18/2017 9:50 AM, Clem Cole wrote:
> On Sun, Sep 17, 2017 at 11:22 AM, Arthur Krewat <krewat at kilonet.net
> <mailto:krewat at kilonet.net>> wrote:
> I have a C compiler for TOPS-10 that I got off the Internet back
> in 1988. Still haven't messed around with it enough to get it to
> run, but ...
> There was a PDP-10 C compiler in the late 1970s, that was kicking
> around CMU, MIT and Stanford which we used to write backup10 and and
> an implementation of tar. IIRC, it was based on the the Ritchie
> front end and was V6 in syntax (i.e. pre-V7 or typesetter C - aka
> 'White Book). I've forgotten the rules of chars, but I remember you
> had to be careful. I think it was 4 9-bit chars to transfer things
> (4*9=36 bits), but I think I remember there were cases on output that
> it wanted to wash it through a 7-bit PDP-10 char (5*7+1 =36bits) which
> was the 'norm' for most languages like SAIL, BLISS et al.
> I did not mess with much, but that time, I was transitioning from the
> 10's to UNIX by that time. I added support for the -20's dumper
> tapes to backup10 which were almost but not quite the same. But that
> was the last I messed with it. Mike Accetta and Fil Aliva (of CMU Mach
> fame) I remember had their had in that subsystem, at one point. And
> of course Danny Klein is always a good one from those days to ask too.
> I'll see if I can dig them up and ask.
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