Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83 based; site houxj.UUCP Path: utzoo!watmath!clyde!cbosgd!cbdkc1!desoto!packard!hoxna!houxm!houxj!wapd From: wapd@houxj.UUCP (Bill Dietrich) Newsgroups: net.micro Subject: Re: 8086 et al status bits question. Message-ID: <450@houxj.UUCP> Date: Fri, 21-Dec-84 16:48:29 EST Article-I.D.: houxj.450 Posted: Fri Dec 21 16:48:29 1984 Date-Received: Sat, 22-Dec-84 07:38:48 EST References: <435@gitpyr.UUCP>, <12@spar.UUCP> Organization: AT&T Bell Labs, Holmdel NJ Lines: 25 I haven't used an 8080-type processor in 8 years or so, but I believe the reason for INC/DEC not touching CARRY is to allow multiple-digit or high-precision math. To add two 200 digit numbers, for example (in pseudo-code) : p1 = pointer to digit of number 1 (source) p2 = pointer to digit of number 2 (source) p3 = pointer to digit of number 3 (destination) *px means digit pointed to by px counter = 200 loop: add with carry *p1 and *p2 putting in *p3, generating carry INC p1 INC p2 INC p3 DEC counter JUMP to loop if counter not zero Bill Dietrich houxj!wapd