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From: hrubin@pop.stat.purdue.edu (Herman Rubin)
Newsgroups: comp.arch
Subject: Re: IEEE floating point
Message-ID: <12805@mentor.cc.purdue.edu>
Date: 26 May 91 00:25:17 GMT
Article-I.D.: mentor.12805
References: <9105250030.AA08036@ucbvax.Berkeley.EDU> <1991May25.222551.16365@zoo.toronto.edu>
Sender: news@mentor.cc.purdue.edu
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In article <1991May25.222551.16365@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes:

			......................

> I will confine myself to observing that IBM hex FP is the only FP format
> I know of that made half the FP instructions -- the single-precision ones --
> just about useless to most programmers.

The IBM hex FP is not that much worse than any other FP with 32-bit words.

Some of the IEEE implementations make the 32-bit FP operations actually 
more expensive than the longer ones, whereas on a machine like the CYBER 205,
especially for vectors, they are much less expensive.  Of course the CYBER
quite properly calls the 32-bit ones half precision and the 64-bit ones 
full precision, and the hardware does make provision for double precision.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet)   {purdue,pur-ee}!l.cc!hrubin(UUCP)