In this post we are going to learn about the What is Real Time System and Types of Real Time System which is very easily explain below. This is very interesting topic. There is trending in Quora also.
What is Real Time System: Definition of RTS
A computer system which is response on the time is known as Real Time System. A system that satisfy bounded response time constraint or risk of system failure.
In real time computing, the correctness is depends on the time at which the results are produced not only depends upon the logical result.
A Deadline is the given time after a event, when a response time has completed.
Key Terms of Real Time System
- The ability of the operating system to provide the necessary level of service in a bound response time
- It responds to inputs immediately(Real-Time)
- Here the task is completed within a specified time delay
- Real time computing is equivalent to fast computing
- Necessary signaling between interrupt routines and task code is handled by RTS
- Real time systems operate in a static environment
- Real-time programming includes assembly coding, priority intercept programming, writing device drivers
Example of Real time system
- In real life situations like controlling a traffic signal or a nuclear reactor or an Aircraft.
- Mobile Phones, Digital Camera , Microwave Oven
- Avionics, Radar Control System, Industrial Process Control
- Command and Control
- Multimedia system
- Electronics Warhead Control System
- Missile Tracking System
Logical / Temporal Correctness
- If a system misses its time limit then the resulting action can be canceled, can continue, depending on the system option.
- Its specification includes logical / temporal correctness
Logical correctness: Indicates that the system should produce the correct output (must be verifiable)
Temporal correctness: Implies that system must produce output at correct or right time
CPU Architectures & Structure of a Real Time System
- The Component of RTOS is its kernel – Monolithic & Microkernel.
Characteristics of Real Time System
- Failure cost is high
- Concurrency and Multi programming Require
- Requirements of Reliability and fault tolerant
- Predictable behavior
- Computation – Offline (p recomputed) and Online (Dynamically)
- Priority – Static and Dynamic
- Scheduling – Preemptive and Non-Preemptive
Now we are going to describe the type of Real Time System.
Type of Real Time System
Real Time system they can be characterized as
- Hard Real Time Systems
- Soft Real Time Systems
- Firm Real Time System
1. Soft Real Time System:
- This System should meet timings constraints. Response time overrun leads to disastrous damage.
- Here utility value becomes less/drops with time
- Exam hall : Delay by 30 minutes allowed. If you very delay then you will not allowed to appear in the exam.
- Word processors
- Airline reservation system
2. Hard Real Time System:
- Deadline overruns are tolerable, but not desired.
- There is no frightening consequence of missing one or more time limits.
- If a task does not meet deadline then the system crashes.
- A difficult time limit is put on a job because late results produced by the job after the deadline can have disastrous consequences.
Example: Onboard computer of a moving aircraft
- Measures velocity, height, position, acceleration, air pressure etc.
- Scheduled time collects data with sensor within 20 minutes
- Compares these data against the stored values
3. Firm Real Time System:
- System doesn’t fail but throws the results (ignores) in case of failure .
- The system doesn’t fail but throws the results (ignores) pass the deadline.
- Every 1/30 second second has to come in the frame.
- Frames will not wait for the destination to arrive, but switch to the next frame if the 6th frame does not arrive
- Hard RTS are not periodic
- Most periodic hard real-time system companies are RT systems
Example: Video Conferencing
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