; Initialize timer interrupt handler
                            ;push ax
                            ;push dx
                            mov  ah, 35h
                            mov  al, TIMER_INT
                            int  21h                        ; Now we have an address of this interrupt handler in bx
                                                            ; since IVT starts at 0x00, bx, an offset, has a definitive address to 1CH handler
                            cli
                            mov  word ptr [TIMER_INT_ADDR], bx ; move address of 1Ch to TIMER_INT_ADDR | Point the 1Ch IP to the TIMER_INT_ADDR.
                            mov  ax, es
                            mov  word ptr TIMER_INT_ADDR[2], ax ; move code segment of the 1Ch int to the addr+2bytes (each entry in IVT is 2 words wide)
                            mov  ax, seg handle_timer           ; new code segment for the interrupt
                            mov  ds, ax
                            mov  dx, offset handle_timer
                            mov  ah, 25h
                            mov  al, TIMER_INT
                            int  21h
                            sti                             ; Ok now we set new address of the 1Ch interrupt handler. Effectively,
                                                            ; it should be DS(handle_timer):DX(offset of handle_timer), so whenever
                                                            ; 1CH is called, it goes to handle_timer

handle_timer:
                            cli
                            inc [timer_count]
                            sti
                            iret