Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: RISC as a "technology window"?
Message-ID: <1989Mar25.053536.27949@utzoo.uucp>
Organization: U of Toronto Zoology
References: <63866@pyramid.pyramid.com>
Date: Sat, 25 Mar 89 05:35:36 GMT

In article <63866@pyramid.pyramid.com> wendyt@pyrps5.pyramid.com (Wendy Thrash) writes:
>If you sell even one system without floating-point hardware, some poor
>programmer (or group) will spend the next twenty years (your product should
>last so long) supporting floating-point operations on systems without the
>floating-point hardware...

The Sun 2/3 line is somewhat a worst case of this, with something like
four different floating-point-hardware configurations.  This is obviously
an enormous headache for Sun and third-party software suppliers.  Some
of the third-party suppliers simply support the 68881 and nothing else,
so their stuff won't run any faster with an FPA and won't run at all on
a 3/50 without 68881.  Sun hasn't got that escape.  It shows, too:  the
specs for the SPARC (at least, the ones I saw, some time ago) say that
there is *one* floating-point architecture, which the kernel must fake
if the hardware isn't there.  (Sun has sort of blown it on the hardware
end for the Sun 4, I gather, but architecturally it makes sense.)
-- 
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