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From: baba@spar.UUCP
Newsgroups: net.micro
Subject: Re: 8086 et al status bits question.
Message-ID: <12@spar.UUCP>
Date: Wed, 19-Dec-84 03:06:01 EST
Article-I.D.: spar.12
Posted: Wed Dec 19 03:06:01 1984
Date-Received: Fri, 21-Dec-84 00:45:55 EST
References: <435@gitpyr.UUCP>
Distribution: net
Organization: Schlumberger Palo Alto Research, CA
Lines: 10

> 
> Is it really useful to be able to do a comparison followed by an INC
> (or DEC), and then be able to do a JC or JNC on the comparison?
> -- 

It makes the equivalent of the C "while(*pointer++ > VALUE)" construct 
more efficient.  In preserving only the carry flag it would appear that
intel learned from their mistake on the 8080, where 16-bit increments 
and decrements don't even affect the zero flag, forcing two additional
instructions into every 16-bit down-counter.