Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!tank!phd_ivo@gsbacd.uchicago.edu
From: phd_ivo@gsbacd.uchicago.edu
Newsgroups: comp.arch
Subject: Re: 80486 vs. 68040 code size
Message-ID: <3150@tank.uchicago.edu>
Date: 10 May 89 01:13:44 GMT
Sender: news@tank.uchicago.edu
Distribution: eunet,world
Organization: University of Chicago Graduate School of Business
Lines: 18

>There seems to be alot of variability though - like a 16Mhz '386 is 
>faster than a NeXt 33Mhz 68030 (both using GCC)?  

Even though some popular magazines have said so, to the best of my knowledge
and all NeXt sales prospectuses, the NeXt runs at 25MHz, not 33 MHz.

Apropos unusual architectures (and Burroughs access checking): being a complete
outsider, I am quite startled by the fact that computers do not implement much
group checking. If we can waste a bit on parity check (how many parity errors
have you had?), why can't we use one to signal READ-ONLY or NO-ACCESS for each
byte? This way, one can put a single No-ACCESS byte between datastructures at
link/load time, which should detect out of pointer ranges much more quickly
than the wait-and-see in use in our systems. (At least I have spent days of my
life searching where wild pointers.) It would also seem that this concept would
go quite well with object-oriented languages, which try to but never can check
if non-member functions access objects.

/ivo welch	phd_ivo@gsbacd.uchicago.edu