说明：  微机原理课程设计报告 课题六：数字闹钟 1. 通过8253定时器产生秒脉冲定时中断。在中断服务程序中实现秒、分、小时的进位（24小时制）。 2. 将当前时分秒在七段LED显示器上显示（如：091132）。 3. 可设置闹钟的时间当前值（对准时间）,设置闹铃时间,闹铃功能的关闭和开放. 关键词:数字闹钟，8253定时器，LED显示器，8255A并行口
(Computer Principles of curriculum design report six topics: digital alarm clock 1. Through the 8253 regular pulse generated timer interrupt. In the interrupt service routine to achieve seconds, minute, hour binary (24 hours system). 2. When the minutes and seconds in the current Seven-Segment LED display shows (for example: 091,132). 3. To set the alarm time to the current value (at the time), set the alarm time, alarm function to close and open. Keywords: digital alarm clock, 8253 Timer, LED display, 8255A Parallel Port)