以单片机为核心器件，组成一个收银机系统，能通过4×4键盘的“0”－“9”键实现商品单价和商品数量的输入，“A”、“B”、“C”、“D”键作为功能键，完成“×”、“＋”、“＝”和清零的功能，并通过LED显示结果。-The microcontroller as the core device to form a cash register system, through the 4 × 4 keypad " 0" - " 9"　key to achieve the number of commodities and commodity price input, " A" , " B" , " C" , " D " keys as function keys, complete " ×" ," +" ," ="　and clear of, and through the LED display results.