data validation (was re self-modifying code)

[Alan T. Bowler [SDG]]

In article <61866 at sun.uucp> guy at gorodish.Sun.COM (Guy Harris) writes:
>>   This is for a machine which happily passes descriptors of arrays
>> around, and manages to bounds-check array references in parallell
>> with the fetch. 
>
>Umm, err, what machine is that?  Doesn't sound like the GE 645 or the
>successors that I knew of; as I remember it, the 645 and the HIS 6180 were
>fairly "conventional" machines in most regards, with no automatic
>bounds-checking for array references.  (Maybe some of the weirdball "indirect
>then tag" addressing modes could do this, but I don't think the PL/I compiler
>made much use of most of them.)

Guy is right.  I think Dave is getting confused with the segmentation
and capability hardware of the other large Honeywell machines.
(L66, DPS-8, DPS-88, DPS-90, DPS-8000 etc).  The Multics boxes
were really just modified DPS-8's, but they did not have the
same capability features.  The protection mechanisms were done
by the same designer, who basically said "what did I do wrong on Multics?".