Re: A82: 2's compliment

To: assembly-82@lists.ticalc.org
Subject: Re: A82: 2's compliment
From: "Eric O'Connell" <titan@gate.net>
Date: Mon, 13 Jul 1998 19:25:47 -0400
Delivered-To: assembly-82-outgoing@towerguard.unix.edu.sollentuna.se
In-Reply-To: <187ea284.35aa95bd@aol.com>
Reply-To: assembly-82@lists.ticalc.org


>This is more of a question for Dines, but I sent it to the list in case anyone
>else could answer it.
>Well, I obviously don't understand 2's compliment, because I couldn't get it
>to work with Dines' routines.
>So............could someone explain how it works?

2's compliment works like this:

The negative of a number (say, 1) is equal to its logical NOT plus 1.

So, 1 = %0000 0001
    NOT(1) = %1111 1110
    +1 = %1111 1111

And 0xff in 2's compliment 8 bit numerics is the number negative one.

Hope this helps,
Eric

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References:

A82: 2's compliment

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