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From: jsp@b.gp.cs.cmu.edu (John Pieper)
Newsgroups: comp.arch
Subject: Re: Other advantages of ternaries (was number bases)
Message-ID: <41@b.gp.cs.cmu.edu>
Date: Fri, 19-Jun-87 02:33:31 EDT
Article-I.D.: b.41
Posted: Fri Jun 19 02:33:31 1987
Date-Received: Tue, 23-Jun-87 01:07:45 EDT
Reply-To: jsp@b.gp.cs.cmu.edu (John Pieper)
Organization: Carnegie-Mellon University, CS/RI
Lines: 26
Keywords: redundant binary adders, parallel multipliers, Booth encoding




> In article <35@b.gp.cs.cmu.edu>, jsp@b.gp.cs.cmu.edu (John Pieper) writes:
> > 
> > One distinct advantage of a (+1, 0, -1) number representation is that no
> > carry-propagation is required for adders. Since the minor cycle of a
> 
> You will still have carry propogation in many instances, even if you always
> do manage to normalize a number. Granted you may not have to carry as OFTEN
> (on the random case), but carry will still be necessary from time to time.

Unless you mean integer overflow (which is always a problem on
fixed-word-length machines) there is no carry propagation. There are carries,
but these are limited to affect at most the next two bits. Since each bit S[i]
of the sum depends only on A[i] thru A[i-2] and B[i] thru B[i-1] of the
operands, we can add in time O(k) instead of O(log n).

See TAKAGI et al, IEEE Trans. Comp., Sep 1985.
-- 
-------------------------------------------------------------
John Pieper				 jsp@n.sp.cs.cmu.edu
Computer Science Department
Carnegie-Mellon University
Pittsburgh, Pa 15213
	"Supersonicous Siliconous"? What we need is Warp speed!