设计倒计时时钟 倒计时：当程序运行时，从59秒递减，以实现倒计时。该实验使用了8253A，8259A，数码管等，以了解这些芯片结合后的硬件设计和软件编程的方法 -Design countdown clock countdown: When program runs, decreasing from 59 seconds to achieve the countdown. The experiment used the 8253A, 8259A, digital tubes, etc.,

用matlab实现clockr仿真，初学试用的小程序-Clock of matlab simulation, a small trial program beginner

EDA技术之数字时钟，带有定时闹钟功能-The EDA technology digital clock, alarm clock with timer function. . . . . . . . . . .