bits 16
        ;; enforce CS:IP
org 7C00h

        jmp 0x0000: start
        tempdata dw 0x0000
start:
        call print_time
        jmp $

;;; Print the time to wherever cursor is
;;; Modified: AX, BX, CX, DX
print_time:
        call get_real_time_clock_time
        mov al, ch
        call print_bcd_byte
        mov al, ":"
        call print_char
        mov al, cl
        call print_bcd_byte
        mov al, ":"
        call print_char
        mov al, dh
        call print_bcd_byte
        ret

;;; Get time of day according to the hardware clock.
;;; Return: (all times in BCD)
;;;    CH = hour
;;;    CL = minutes
;;;    DH = seconds
;;;    DL = daylight savings flag. 0x0 = standard, 0x01 = daylight savings.
;;;    CF is clear if successful/set on error.
get_real_time_clock_time:
        mov ah, 0x02
        ;; clear CF (look up how)
        int 0x1a
        ret

;;; Print a binary coded byte (two numbers) to where point is.
;;; Input:
;;;    AL = BCD number to print
;;; Modified: AX, BX
print_bcd_byte:
        push ax
        shr al, 4
        add al, 0x30
        call print_char
        pop ax
        and al, 0x0f
        add al, 0x30
        call print_char
        ret

;;; Display a single character on the screen.
;;; Input:
;;;    AL = character to write
;;; Modified:
;;;    AH - Set to 0x0e
;;;    BX - zeroed out.
print_char:
        mov ah, 0x0e
        ;;clear to 0, lest unexpected color changes happen.
        xor bx, bx
        int 0x10
        ret