Q about DEC 
Author Message
 Q about DEC

What happens if

mov    ax,0h
dec    ax

What happens?
Is ax decremented to FFFFh?
Flags set?

Is it the same thing with SUB?

mov    ax,0
sub    ax,10

What happens?

--
Netrunner

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<WWW: http://www.*-*-*.com/ ~hugopa           >
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Tue, 10 Aug 1999 03:00:00 GMT  
 Q about DEC

Quote:

> dec    ax
> Is it the same thing with SUB?

No. DEC doesn't affect Carry flag. Look opcode list for details.


Tue, 10 Aug 1999 03:00:00 GMT  
 Q about DEC

: What happens if

: mov    ax,0h
: dec    ax

: What happens?

  ax = -1 = 0ffffh  The carry flag is not set

: Is it the same thing with SUB?

: mov    ax,0
: sub    ax,10

: What happens?

  ax = -10 = 010000h-10  The carry flag is set



Wed, 11 Aug 1999 03:00:00 GMT  
 Q about DEC

Hello everyone,

This is great. I just managed to implement an x86 CPU in JAVA.
If you have javascript enabled and Netscape 3.0 then look at this link.
http://www.*-*-*.com/
This is just a demo.
I guess this is a de{*filter*} that can be used on the web??? LOL

Paul

Quote:

> What happens if
> mov    ax,0h
> dec    ax
> What happens?
> Is ax decremented to FFFFh?
> Flags set?
> Is it the same thing with SUB?
> mov    ax,0
> sub    ax,10
> What happens?



Fri, 13 Aug 1999 03:00:00 GMT  
 
 [ 4 post ] 

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