Why can't DL contain my address?

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Adcock

Joined: 09 Aug 2017
Posts: 4

Adcock 08 Oct 2018, 06:44

Code:

org 256
mov [wtf],11110111b
mov dl,[wtf]
mov ah,2
int 21h
int 20h
label wtf byte
db 0b

Why this works but not this.

Code:

org 256
mov [wtf],11110111b
mov dl,wtf
mov ah,2
int 21h
int 20h
label wtf byte
db 0b

The following works too. [Regardless of output]

Code:

org 256
mov [wtf],11110111b
mov dx,wtf
mov ah,9
int 21h
int 20h
label wtf byte
db 0b

Edit :

Wait wait. I think I got it.
Cause address is 16 bit but dl is 1 byte.
Right?

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08 Oct 2018, 06:44

CandyMan

Joined: 04 Sep 2009
Posts: 414
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop

CandyMan 08 Oct 2018, 07:22

Because you used "org 256" directive. Address of wtf is bigger than 255 and the register dl is 8-bit (0..255 unsigned value).

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08 Oct 2018, 07:22

DimonSoft

Joined: 03 Mar 2010
Posts: 1228
Location: Belarus

DimonSoft 09 Oct 2018, 09:59

Adcock wrote:

Wait wait. I think I got it.
Cause address is 16 bit but dl is 1 byte.
Right?

Exactly.

09 Oct 2018, 09:59

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