.model tiny
.code
.186
org 100h

start proc near
      mov ax,351ch
      int 21h
      mov word ptr old_int1ch,bx
      mov word ptr old_int1ch+2,es


      mov ax,251ch
      mov dx,offset int1ch_handler
      int 21h
; программы код
      mov ah,1
      int 21h

      mov ax,251ch
      mov dx,word ptr old_int1ch+2
      mov ds,dx
      mov dx,word ptr cs:old_int1ch
      int 21h

      ret
      old_int1ch dd ?
      start_position dw 0

      start endp

      int1ch_handler proc far
      pusha
      push es
      push ds
      push cs
      pop ds
      mov ah,02h
      int 1ah
      jc exit_handler ; если часы заняты
      ; ал часы

      call bcd2asc
      mov byte ptr output_line[2],ah
      mov byte ptr output_line[4],al

      mov al,cl

      call bcd2asc

      mov byte ptr output_line[10],ah
      mov byte ptr output_line[12],al

      mov al,dh
      call bcd2asc
      mov byte ptr output_line[16],ah
      mov byte ptr output_line[18],al

      mov cx, output_line_1
      push 0b800h
      pop es

      mov di,word ptr start_position
      mov si,offset output_line
      cld
      rep movsb

      exit_handler:
      pop ds
      pop es
      popa
      jmp cs:old_int1ch

      bcd2asc proc near
            mov ah,al
            and al,0fh
            shr ah,4
            or ax,3030h
            ret
            endp


      output_line db ' ', 1fh, ' ', 1fh, '0', 1fh, 'h', 1fh
                  db ' ', 1fh, '0', 1fh, '0', 1fh, ':', 1fh
                  db '0', 1fh, '0', 1fh, ' ', 1fh
       output_line_1 equ $ - output_line
       int1ch_handler endp
       end start