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From: oconnor@sunray.steinmetz (Dennis Oconnor)
Newsgroups: comp.arch
Subject: Re: What should be in hardware but isn't
Message-ID: <7587@steinmetz.steinmetz.UUCP>
Date: Fri, 9-Oct-87 15:25:20 EDT
Article-I.D.: steinmet.7587
Posted: Fri Oct  9 15:25:20 1987
Date-Received: Sun, 11-Oct-87 16:34:24 EDT
References: <581@l.cc.purdue.edu> <8646@utzoo.UUCP> <705@gumby.UUCP> <8668@utzoo.UUCP> <30382@sun.uucp>
Sender: root@steinmetz.steinmetz.UUCP
Reply-To: oconnor@sunray.UUCP (Dennis Oconnor)
Organization: General Electric CRD, Schenectady, NY
Lines: 41

In article <30382@sun.uucp> lyang@sun.UUCP (Larry Yang) writes:
>How much more time would Motorola buy if they didn't do transcendentals
>in micro/nanocode and had software engineers write libraries that they
>could sell to customers?  Could the 881 be fit onto a smaller die (i.e.,
>easier layout, better yield)?  What's wrong with Motorola saying:
>"Here's this wonderful fp chip we've made.  It does all the basic
>fp operations really fast.  If you want to do sin, cos, and stuff, then
>here are the software library routines that are guaranteed to work."
>Are there no competent software engineers at these IC houses?

Anyone who can write microcode for the chip considered the STANDARD
( as in, if you and the '881 disagree on a result , you are wrong )
for IEEE floating point MUST be a competent software engineer.

>I'll have to admit that I haven't designed any floating point arithmetic,

Actually, I could tell this without you admitting it, so you need't have.

>so if I'm way off base, someone please correct me. (Of course, I didn't
>have to request this... :-) But it would seem that much would be gained
>from the chip design/fab/test area if the sweating over complex functions
>would be moved to the software realm.
>
>--Larry Yang [lyang@sun.com,{backbone}!sun!lyang]
>  Sun Microsystems, Inc., Mountain View, CA      

Right, great idea (sarcasm). For every operation currently done
in the '881 in microcode, make the user fetch an instruction from
i-mem. Boy, that'll improve performance! (heavier sarcasm).
Hey, and don't forget to use plenty of the available user
registers in these routines.

The 68000, '010 and '020 family are NOT RISCs. Putting a RISCy
FP Coprocessor on them makes as much sense as putting a
telescopic sight on a sawed-off shotgun : different design
contexts bring about different solutions.

--
	Dennis O'Connor 	oconnor@sungoddess.steinmetz.UUCP ??
				ARPA: OCONNORDM@ge-crd.arpa
        "If I have an "s" in my name, am I a PHIL-OSS-IF-FER?"