7. Open Loop System

There are two types of computer control system:

1. Open loop system
2. Feedback system

The first type, Open Loop System, only looks at its input signal in order to decide what to do.

It takes no account at all of what is happening to its output.

Examples of 'open-loop' systems:

a) You set the microwave oven to run for two minutes.  After cooking
for two minutes, the control system turns the microwave off. It has no idea whether your food is still frozen, burnt or cooked perfectly.

b) You program the video recorder to start recording the football game at 7.30pm. However, because the news program finished early, you miss the first vital 15 minutes of the match. Because the system is only checking its input(time), it had no idea that the starting time of the match had changed.