[Simh] Pascal 1.3 manual for RSX 11 4.6 - warning, nostalgia trip!

[brian]

On Tue, 2 Feb 2016 15:03:36 +0000, Jason Armistead wrote:

>Al Kossow wrote:
>
>> here is the SPD
>>
>> http://h18000.www1.hp.com/info/SP1418/SP1418PF.PDF
>
>And the second page of the SPD even mentions "On-line Debugging Technique (ODT)" - the topic of one of our other recent SIMH mailing list threads !!!
>

It's more than 30 years now since I last used Pascal on the PDP-11
(RSX-11M 4.1, no PLUS). AFAIK, RSX Pascal was derived from what we
had, which was Oregon Pascal. I believe that DEC subsequently bought
it to release as the first version of RSX Pascal. Oregon Pascal was
one of two Pascal compilers that were available for the PDP-11 in
those days, I think the other one was called Whitesmiths, but I'm not
100% sure. 

Oregon Pascal was BY FAR superior, we found out after a trial run or
two that Whitesmiths Pascal was actually a translator rather than a
compiler, they had a 'C' compiler, and their Pascal 'compiler'
actually translated to 'C' and then compiled the resulting 'C' code.
If you told it to stop at MACRO-11 sources (both compilers could do
this) then the Whitesmiths code was MONUMENTALLY inefficient compared
to the Oregon code. 

We were doing British Ministry of Defence '0521' standard coding,
which meant that the code had to withstand not just user idiocies but
a knowledgeable user who was attempting to break it. We licensed the
library sources from Oregon, and I got the job of digging through them
and intercepting ctrl-C from the user (the program had to ask whether
they wanted to abort it and exit gracefully if so) and also I remember
about six weeks of hacking around in MACRO making sure that the user
couldn't break things by giving it an (aliased) output device such as
a lineprinter as the input device. Probably it would have taken an
experienced MACRO programmer about 30 minutes in total, but I was
still  learning MACRO-11 at that point, programmers were in
sufficiently short supply that the company had taken me on as a
programmer from being a chemistry Ph.D. whose claim to computer
experience was that I had done a bit of number crunching under
Algol-60!

I missed the thread about ODT, but I sure remeber having to use it,
The debugger supplied with the compiler was just about capable of
debugging 'Hello world' before the code got so large that it broke the
limits, even with overlays. All of our debugging had to be done by
compiling to MACRO and then patching breakpoints into the executable. 

The other 'interesting' part of it was writing the overlay structure
for the linker. For a big program, trying to get every branch within
32 KB  could be almost as much work as writing the code! The hell with
logical program design, you wrote your code first and then came the
tricky part, hacking it all around to get within that limit. I
remember breaking the linker (task builder) at one point because of
trying to break the code down into too many branches. 

I didn't see what DEC did to the libraries after they bought Oregon
Pascal, but I am 100% certain that all the libraries we had to link
against lived under [1,1]. I was (I think) the only programmer on the
team who used DCL in preference to MCR, but our editors were K52 (for
the VT 52 terminals) and KED (same editor but for the VT 100s). There
was also a MAKE utility which was available, but the problem with that
was that it burned so much CPU trying to work out what to compile on a
big program that the PDP-11 just slowed to a crawl (there were about a
dozen of us developing on that one machine) so it ended up that we
were only allowed to run one MAKE a day after everyone had gone home. 

Fun times, though. :) 


Brian.