并行口实现数字0~9、A~F、L、U、P、n总共19个键盘，将按键的结果用4位数码管（例如：7SEG-MPX-CA-BLUE）显示（可选——按键控制移位）出来。-Parallel port of the numbers 0 to 9 and A to F, L, U, P, n a total of 19 keyboard, the keys with the four digital tube (for example: 7SEG-the MPX-CA-BLUE) (optional- button control shift).