Define essential properties of real-time operating system?

Answer 1

A typical real-time operating environment we note that the computer system has an interface which is embedded within its environment. The operating system achieves the desired extent of regulation as follows:

1. Sense an event: The system monitors its operative environment using some sensors. These sensors keep a tab on some measurable entity. Depending upon the context of use this entity may be a measure of temperature, or a stock price fluctuation or fluid level in a reservoir. These measurements may be eriodic. In that case the system would accept an input periodically. In case the measurement of inputs is taken at specified times of operation then the OS may schedule its input at these specified times or it may be interrupted to accept the input. The input may even be measured only when an unusual deviation in the value of the monitored entity occurs. In these cases the input would certainly result in an interrupt. Regardless of the input mode, the system would have an input following a sensor reading (which is an event).