Path: utzoo!attcan!uunet!lll-winken!ubvax!ardent!mrk!mac
From: mac@mrk.ardent.com (Michael McNamara)
Newsgroups: comp.arch
Subject: Re: Wafer Scale Floating Point chip
Keywords: silicon frisbee(tm) floating point
Message-ID: <1879@ardent.UUCP>
Date: 18 Jan 89 00:11:19 GMT
References: <335@belltec.UUCP> <34593@bbn.COM>
Sender: news@ardent.UUCP
Reply-To: mac@mrk.ardent.com (Michael McNamara)
Organization: Ardent Computer Corporation, Sunnyvale, CA
Lines: 20

In article <34593@bbn.COM> slackey@BBN.COM (Stan Lackey) writes:
|In article <335@belltec.UUCP> jom@belltec.UUCP (Jerry Merlaine) writes:
|>If you want to do something useful with wafer scale technology, build
|>me an IEEE floating point look-up table ROM.
|
|I have a pair of ECL floating point chips on my desk that do DP add,sub,
|and mul in under 60ns.  Lookup tables used to sound great, but
|technology marches on...
|-Stan

	How fast do they do a square root? exponential? how about
ATAN2 ?  A lookup table that gets you close to the answer in 150ns
followed by a 3-4 term polynomial (Running on your 60ns parts,
perhaps) is how we do trancendental functions these days...

	Implementing the same T.F. with just + - * can take hundreds
of cycles.
	
Michael McNamara 
  mac@ardent.com