[Info-vax] OT: obscure PDP11 OSes (even more dinosaury)

[Paul Sture]

On 2015-06-16, Paul Hardy <p.g.hardy at btinternet.com> wrote:
> Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> wrote:
>> 
>> I've forgotten most of the day to day overlay issues I encountered
>> but that was one of the big ones I remember.
>
> I built big programs on RSX11M, including one using using over 100 overlays
> in a multi-branching tree.  The main problems were avoiding cross calling
> between overlays in different branches of the overlay tree - the call would
> work fine, but when you came to return, the caller had been overwritten by
> the incoming overlay! This was hell to debug. We moved to a VAX and
> breathed a sigh of relief at laying out the code flat. 

I once had the same problem on RT-11 and Time Shared Dibol (TSD).
Returning from the offending routine would take down the whole of TSD
and thus all users with it. Oops.

That was in important lesson in testing however.  The guilty routine
was the one that reported fatal application errors so in the normal
course of events was only triggered by a bug elsewhere.

-- 
I don't know what the language of the year 2000 will look like, but I
know it will be called Fortran.                    -- Tony Hoare 1982