Aucbvax.2059
fa.works
utzoo!duke!decvax!ucbvax!RYLAND@SRI-KL
Fri Jul 3 09:35:48 1981
Re: Addressing and File Accessing
Bill, the system you describe (System 38) is just a
capability-based machine, which is certainly old hat by now.
Unfortunately, this idea still seems to be barely catching on in
the "real world." Most of the seminal systems (CAL at Berkeley,
Hydra at CMU, and the Plessey System 250) were done and finished
years ago, and yet there are only a few commercial systems which
reflect this elegance of architecture (S38, Intel's 432 (in some
sense), some ICL machines). Others are working on systems which
embody these ideas (H-P's Bridge project, the S-1 project), but
most of them bastardize the design for "practicality". I surmise
that capability-based systems are finding life difficult because
no one ultimately understands how to deal with them practically
(e.g., the Hydra folks discovered quite a few problems with
accounting (who owns an object?), backup, recovery, etc., though
they also made great strides with some of the harder issues
(mostly reliability).) I think a large percentage of us would
be delighted to have a true capability-based machine if the
performance were up to what we've come to expect from current
architectures, but that doesn't seem to be around the corner (at
least in any useable way: S38 hides all its good design from the
user and masks it in the usual nonsense IBM business software.)
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