- In real-time computing, real-time deals with guarantees not with raw speed.
- Adding a high-end processor, more RAM or faster bus interface doesn’t make a system real-time.
- A real-time system deals with guarantees, not with promises.
A real-time system is one in which the correctness of the completion does not only depend upon the logical correctness of the computation but also upon the time at which the results are produced. If timing constraints are not met, system failure is said to have occurred.
In the above plot, the responds time of each iteration of a Real-time application (RTA) remains constant whereas for Non-real time application (NRTA) the response time is not at all constant.
RTAs are time deterministic applications, which means their response to events is almost constant. Depending on the response timing the RTAs are classified into two.
- Soft real-time application
- Hard real-time application
The response time of Soft RTAs could make a small deviation in terms of milliseconds or even seconds whereas the Hard RTAs must complete within a given time limit, failure to do so will result in absolute failure of the system.
Next Chapter: RTOS vs GPOS (In terms of Task Scheduling)