funcs.asm

; functions 

gfxmode:
    xor ax,ax
    mov al,0x13 
    int 0x10 
    ret

keypress:
    mov ah,0x00
    int 0x16
    ret
    
reboot:
    jmp long 0xffff:0x0000

putpix:
    mov cx,320 
    mul cx      ; multiply ax (Y) by 320
    add ax,bx   ; add bx (X) to ax (Y)
    mov di,ax   ; pixel position is now in di
    mov byte [es:di], dl  ; move dl (colour) to video memory
    ret

start:
    call gfxmode 
    mov ax,0xa000
    mov es,ax     ; vga register to es

    mov ax,50
    mov bx,50
    mov dl,0x0f ; white
    call putpix 
    call keypress
    call reboot