interrupt:

    if TestBit(INTCON, RBIF) = 1 then
      if PORTB.4 = 1 then
        Lcd_Cmd(LCD_CLEAR)
        Lcd_Cmd(LCD_CURSOR_OFF)
        Lcd_Out(1,1,"RB4")
        DELAY_MS (100)
      else
        if PORTB.5 = 1 then
          Lcd_Cmd(LCD_CLEAR)
          Lcd_Cmd(LCD_CURSOR_OFF)
          Lcd_Out(1,1,"RB5")
          DELAY_MS (100)
        else
          if PORTB.6 = 1 then
            Lcd_Cmd(LCD_CLEAR)
            Lcd_Cmd(LCD_CURSOR_OFF)
            Lcd_Out(1,1,"RB6")
            DELAY_MS (100)
          else
            Lcd_Cmd(LCD_CLEAR)
            Lcd_Cmd(LCD_CURSOR_OFF)
            Lcd_Out(1,1,"RB7")
            DELAY_MS (100)
          end if
        end if
      end if
    end if