[Info-vax] Whither VMS?

[Robin Fairbairns]

 Jordi Guillaumes i Pons <send.me at no.spam> writes:
>En/na VAXman- @SendSpamHere.ORG ha escrit:
>> 
>> Envision Rod Sterling walking out from the background darkness into the 
>> shadowy light, camera focused on him from his lapel and tie, and with a
>> cigarette lit and its smoke encircling his head...
>> 
>>     "Picture, if you will, a man who has just consumed too much wine 
>>      or too much LSD or who has simply fallen squarely upon his pate
>>      from an appreciable height, and is now totally delusional in the 
>>      usenet newsgroup of comp.Twilight.Zone..."
>> 
>> Where's this VAX exec bit?  
>
>Perhaps in my imagination? I don't read about VAX arch and VMS internals 
>sinde the early nineties, but I _think_ the entries in the page table 
>have a protection mask allows marking a page as readable, but 
>non-executable. I am wrong on that? Too many years, too much coffee and 
>too many arch changes in my life... :(

well, i have this "vax11 780 hardware handbook" on my shelf, so i
pulled it down and looked at it.  no mention of any execute-permission
bit in there.

remember, the later pdp 11 models had i-space and d-space, but i never
encountered anyone using them.  this was, of course, because the
pdp-ll architecture made it really rather difficult: this may have put
off the designers of the vax (for what i would consider irrational
reasons -- the vax architecture would have been far more amenable to
such a split).

of course, the design predated the morris worm, and back then there
was far less emphasis on this sort of code cleanliness.  the
industry's older and wiser now (even if some of its workers still rush
around like rabid rabbits).
-- 
Robin Fairbairns, Cambridge