Re: the IN instruction

Kim Bozman (kbozman379@hotmail.com) Sun, 20 Feb 2000 17:05:31 PST 

From: "Kim Bozman" <kbozman379@hotmail.com>
Subject: Re: the IN instruction
Date: Sun, 20 Feb 2000 17:05:31 PST



Hi Andrew,

The following is taken out of the Intel instruction set.  You to it off the 
elec379 web page:

IN  - transfers a byte or word from an input port to the AL register or the 
AX register, respectively.

Therefore, when you say "IN AL,DX" you will only intake a byte.  If you 
change the line to "IN AX,DX" you will intake the word.

I don't think you can replace the IN command since it uses port numbers and 
"MOV AL,[BX]" will use the address 224H instead of port 224H.

Hope this helps,
Kim

>From: "Andrew Yung" <ayung@physics.ubc.ca>
>To: <eece379@casas2.ece.ubc.ca>
>Subject: the IN instruction
>Date: Sun, 20 Feb 2000 16:21:28 -0800
>
>I have the following piece of code:
>
>MOV	DX,224H
>IN	AL,DX
>
>Will the IN instruction try to load al with the _word_ in DX or the _byte_?
>
>Could I just replace this code with:
>
>MOV	BX,224H
>MOV	AL,[BX]
>
>to achieve the same result, or is there something special about the IN
>instruction?
>
>Thanks!
>

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