Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site kobold.UUCP Path: utzoo!linus!security!genrad!grkermit!masscomp!kobold!tjt From: tjt@kobold.UUCP Newsgroups: net.arch Subject: Re: Complement Arithmetic Message-ID: <262@kobold.UUCP> Date: Fri, 27-Jan-84 21:22:22 EST Article-I.D.: kobold.262 Posted: Fri Jan 27 21:22:22 1984 Date-Received: Wed, 1-Feb-84 01:32:31 EST References: <1425@burdvax.UUCP> Organization: Masscomp, Westford, MA Lines: 17 As I recall, the biggest problem with "positive and negative zero" in one's complement arithmetic is the natural tendency to regard the "positive" zero as the true zero, whereas any additive or subtractive operation would naturally produce the "negative" zero. Some machines attempted to automagically convert this to "positive" zero, but usually failed for some case or other. I don't remember the details but I think it was something to do with a direct implementation of subtraction of a positive number from a negative number when the subtraction is implemented differently than complementing the second operand and adding. While we're at it, what about sign-magnitude representations? These have the same "positive and negative zero" problem, although we seem to be able to tolerate it for floating point. -- Tom Teixeira, Massachusetts Computer Corporation. Westford MA ...!{ihnp4,harpo,decvax}!masscomp!tjt (617) 692-6200 x275