The C compiler we had at NMT that Greg Titus wrote/rewrote allowed one to
pick a number
of different choices for character size (5, 6, 7 or 8). It defaulted to 7
or 8. I recall that the
defaults produced OK results for student work, but that was a bit slow for
pushing the
envelope without some very careful choices. But it was good enough for me
to write
my OS group project running under 'ZAYEF' a DecSystem-20 emulator running
on the
DecSystem 20 under TOPS-20... My first exposure to virtual machines... It
was a total
trip to have 18 bit pointers and weird interrupt semantics....

I really rather working on the VAX 11/750 in 'C' and later on the Sun3/50s
more, though.
In part because the debugger was better (or at least more approachable by my
poor undergraduate mind).

Warner

On Thu, Jul 15, 2021 at 1:28 PM Clem Cole <clemc@ccc.com> wrote:

> The 'second' C compiler was a PDP-10 and Honeywell (36-bit) target Alan
> Synder did for his MIT Thesis.
> It was originally targeted to ITS for the PDP-10, but it ran on Tops-20
> also.
>
> My >>memory<< is he used a 7-bit Character, ala SAIL, with 5 chars stored
> in a word with a bit leftover.
>
> You can check it out:  https://github.com/PDP-10/Snyder-C-compiler
>
> I believe that C compiler Nelson is talking about I believe is actually
> Synder's that Jay either ported from ITS  or WAITS.
>
> We had some form of the Synder compiler on the PDP-10's at CMU in the late
> 1970s.
> It was either Mike Accetta or Fil Aleva that wrote a program to read
> PDP-10 backup tapes, that I updated to deal with TOPS-20/TENEX 'dumper'
> format which was similar/only different.
> ᐧ
>
> On Thu, Jul 15, 2021 at 3:03 PM Norman Wilson <norman@oclsc.org> wrote:
>
>> Nelson H. F. Beebe:
>>
>>   P.S. Jay was the first to get Steve Johnson's Portable C Compiler,
>>   pcc, to run on the 36-bit PDP-10, and once we had pcc, we began the
>>   move from writing utilities in Pascal and PDP-10 assembly language to
>>   doing them in C.
>>
>> ======
>>
>> How did that C implementation handle ASCII text on the DEC-10?
>> Were it a from-scratch UNIX port it might make sense to store
>> four eight- or nine-bit bytes to a word, but if (as I sense it
>> was) it was C running on TOPS-10 or TOPS-20, it would have had
>> to work comfortably with DEC's convention of five 7-bit characters
>> (plus a spare bit used by some programs as a flag).
>>
>> Norman Wilson
>> Toronto ON
>>
>