Re: A82: NEG and CPL

To: assembly-82@lists.ticalc.org
Subject: Re: A82: NEG and CPL
From: ADAMMAN106@aol.com
Date: Sun, 15 Nov 1998 19:23:56 EST
Delivered-To: assembly-82-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-82@lists.ticalc.org

In a message dated 11/15/98 7:38:47 AM Eastern Standard Time,
wouter.demuynck@student.kuleuven.ac.be writes:

> One question:
>  
>  What's the difference between NEG and CPL again? NEG gets the two's 
>  complement and CPL the one's compliment, but how is that one's 
>  complement calculated?
>  
>  Suppose A = $14
>  
>  What will be the result of NEG A and CPL A ?
>  
>  Thanks
>  
>  Wouter

NEG = negate accumulator (not NEG A, just NEG)
CPL = compliment accumulator (not CPL A, just CPL
CPL is (i think) the same as XOR $FF unless the flags are set differently.
You just reverse every bit in A.
So if A is $14, which is %0001 0100...
CPL gives %1110 1011 which is $EB
NEG gives %1110 1100 which is $EC
the difference between one's compliment and two's compliment is the addition
of one
Hope that helped...

~Adamman