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From: sambo@ukma.UUCP (Inventor of micro-S)
Newsgroups: net.unix
Subject: Re: Floating point numbers on the Pyramid
Message-ID: <1925@ukma.UUCP>
Date: Fri, 28-Jun-85 04:08:57 EDT
Article-I.D.: ukma.1925
Posted: Fri Jun 28 04:08:57 1985
Date-Received: Sat, 29-Jun-85 01:21:42 EDT
References: <292@eneevax.UUCP> <2405@topaz.ARPA>
Reply-To: sambo@ukma.UUCP (Inventor of micro-S)
Organization: Univ. of KY Mathematical Sciences
Lines: 36

In article <2405@topaz.ARPA> vijay@topaz.ARPA (P. Vijay) writes:
>	Could someone tell me how the Pyramid 90x
>	does floating point numbers? Somebody told
>	me it was the IEEE floating point std.

Everything you mentioned is specified by the IEEE standard.  (Actually, I
suppose you misquoted whatever source you used for the meanings of the single
and double precision formats - when e = 0 or 255 for single and 0 or 2047 for
double, the numbers are interpreted differently, so the formula you stated
applies only for the range 0 < e < 255 for single, and 0 < e < 2047 for
double.)  If the Pyramid conforms to the IEEE standard, then it must also
be able to simulate single-precision arithmetic (even if the numbers are
all double-precision); it must have four rounding modes; it must be able to
detect five different kinds of exceptions (invalid operation, division by zero,
overflow, underflow, and inexact), possibly providing a way of doing exception
handling; it must implement floating-point operations (including the basic
arithmetic operations) in the manner specified; and it must have at least two
different kinds of NaNs (Not a Number) and both a positive and negative
infinity.

I'm not sure to what address you should write to get a copy of the standard,
though I'm sure you can find out by contacting Richard Karpinski at:
   Dick Karpinski    Manager of Unix Services, UCSF Computer Center
   UUCP: ...!ucbvax!ucsfcgl!cca.ucsf!dick   (415) 666-4529 (12-7)
   BITNET: dick@ucsfcca   Compuserve: 70215,1277  Telemail: RKarpinski
   USPS: U-76 UCSF, San Francisco, CA 94143
I have a copy of the IEEE P754 Draft 10.1 of the standard in front of me,
which I have been told has been adopted as the official standard.
-----------------------------------------
Samuel A. Figueroa, Dept. of CS, Univ. of KY, Lexington, KY  40506-0027
ARPA: ukma!sambo<@ANL-MCS>, or sambo%ukma.uucp@anl-mcs.arpa,
      or even anlams!ukma!sambo@ucbvax.arpa
UUCP: {ucbvax,unmvax,boulder,oddjob}!anlams!ukma!sambo,
      or cbosgd!ukma!sambo

	"Micro-S is great, if only people would start using it."