I wrote a program in assembler and compiled it. It is meant to print a blue smiley face and then wait for the user to press a key before it terminates. It does do that last bit but it doesn't print the smiley face. Can someone explain what have I done wrong ?
CSEG segment
org 100h
Begin:
mov ax,0B800h
mov es,ax
mov di,0
mov ah,31
mov al,1
mov es:[di],ax
mov ah,10h
int 16h
int 20h
CSEG ends
end Begin
I compiled it with MASM with a 16 bit linker
You can only poke the video buffer directly if you're in a text-only video mode. I'm guessing that you're using Windows of some kind and not actually booting DOS, so you probably are in a graphics mode.
What you may be able to do is open a console window and then AltEnter to go to a full-screen text mode. Try running your program there.