React Quickly or Feel the Pain

　　React Quickly or Feel the Pain

　　很多工作我们在XMOS是关于“实时编程”，它是退一步思考，这实际上意味着什么。一般来说，实时编程是一种系统，其中系统的某些操作必须满足特定的截止日期。这些期限可能是系统内部或外部的。通常，这种系统被分成“软”或“硬”实时。如果截止期错过，硬实时系统会发生灾难性的故障，而如果错过了截止期，软实时系统会出现质量下降，但系统至少可以继续工作。

　　处理实时系统时的关键特性是响应时间。一个系统的响应时间仅仅是对外部刺激的响应需要多长时间。这是我们想在XMOS很多。

　　有一个流行的儿童游戏的典型响应时间。它有时被称为“红手”或“打”，但都在不同的世界各地的其他名称。它包括两个人把手放在他们面前，手掌合十，好像在祈祷。球员们把手向前伸，互相触摸指尖。

　　The game has a “slapper” and an “avoider”。 The aim for the slapper is to break contact and slap the avoider’s hands as hard as possible. The avoider needs to move their hands out of the way before they are slapped - if they do this successfully then the avoider becomes the slapper and get their chance at revenge.

　　This game is a great example of a real-time system and a need for a good response time. The slapper provides the external stimulus， and the avoider is the real-time system that must respond. Similarly， in electronic hard real-time systems， sometimes you need to be able to respond quickly or really feel that pain.