Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!husc6!im4u!ut-sally!nather
From: nather@ut-sally.UUCP (Ed Nather)
Newsgroups: comp.arch
Subject: Re: negative addresses (really unsi
Message-ID: <11618@ut-sally.UUCP>
Date: 15 May 88 19:28:51 GMT
References: <11571@ut-sally.UUCP> <28200145@urbsdc>
Organization: U. Texas CS Dept., Austin, Texas
Lines: 29

In article <28200145@urbsdc>, aglew@urbsdc.Urbana.Gould.COM writes:
> 
> >[Ed Nather]:
> When I gather data from stars, I
> >count the precious photons one at a time, and use unsigned arithmetic to
> >massage them, since there are no negative photons (unlike negative addresses).
> What do you care if you are counting in a signed integer, and just
> use half the range?

Unfortunatly I have found no simple way to get the star to cooperate with
respect to counting rates.  Sometimes 16 bits are enough, sometimes 32
aren't, depending on the the star's brightness and the rapidity with which
it varies.

But these are details.  What we are all doing, in different disciplines, is
conforming to current computer architecture rather than cutting it to fit our
particular problem.  Compilers are just a way to insert a "virtual architecture"
in between the user and the hardware so it looks different -- friendlier to 
certain applications, usually.

We pay the cost at run-time.  If we can afford it, fine.  But we continue to
ask more and more of computers as they get faster and faster, and I doubt
this is likely to change any time soon.

-- 
Ed Nather
Astronomy Dept, U of Texas @ Austin
{allegra,ihnp4}!{noao,ut-sally}!utastro!nather
nather@astro.AS.UTEXAS.EDU