[Info-vax] Suggestion: Enhance DCL to support proper escape quoting.

[Paul Hardy]

Johnny Billquist <bqt at softjar.se> wrote:
> On 2022-01-24 23:22, Jan-Erik Söderholm wrote:
>> Den 2022-01-24 kl. 18:24, skrev Bill Gunshannon:
>>> On 1/24/22 09:00, Simon Clubley wrote:
>>>> On 2022-01-21, Dave Froble <davef at tsoft-inc.com> wrote:
>>>>> 
>>>>> I'll admit to learning much from overlays, but, it was still torture ..
>>>>> 
>>>> 
>>>> I learnt a lot from overlays, such as never wanting to go near the
>>>> bloody things ever again in my life. :-)
>>> 
>>> Funny how I always hear this.  I have done lots of overlays on
>>> Ultrix-11 (even for the kernel!) and never had any serious problems
>>> with them.  I even like them.  :-)
>>> 
>>> bill
>>> 
>>> 
>> 
>> I never thought anything bad/good about them, the overlay feature
>> was just that, a feature of RSX-11M. I think the most "overlayed"
>> image I built was using both the RMS libraries and the DTR-11
>> callable library. It was mainly DTR-11 that added most overlays,
>> as I remember it. I think the FMS libs was used also...
> 
> The "worst" of it is when you need to juggle things a lot in order to 
> fit it all in. That can be quite an exercise. Multiple co-trees, 
> figuring out dependencies, and writing the ODL file for it all.
> 
> When I backported DUNGEON V3.2 to RSX, I really had to work hard on 
> that. Probably the most complex thing I've ever done. I think I ended up 
> with 10 co-trees, and all kind of cruft. I would agree that they are not 
> the most fun, but you sortof live with them and accept them. Sure, I can 
> understand people who felt relief when moving to VMS, and never having 
> to care about that again.
> 
>   Johnny
> 

For big programs with many complex overlays it was hell to debug overlay
tree calling mistakes. You should only call to branches up the current tree
or down towards the root of the current branch. If you called across to
another parallel branch it all worked until you tried to return from the
call , where the rest of the calling routine had been overlaid and
obliterated. I remember several late nights debugging such for an early
digital mapping system on RSX11M. 

Moving to the flat address space of VMS was a delight!

-- 
Paul at the paulhardy.net domain