A real-time operating system (RTOS) is defined as one where tasks must complete within prescribed deadlines, with failure resulting in serious consequences. There are two main types of RTOS: hard real-time, which cannot miss deadlines without disastrous effects, and soft real-time, which can miss deadlines occasionally without severe repercussions. Advantages of RTOS include efficient resource usage and low error rates, while disadvantages include limited multitasking and complex scheduling.

1. Real Time Operating System :
Definition :
“Real time operating system is that operating
system in which each task perform their function
with in “Prescribed Deadline” and “Failure” to
these deadlines cause serious consequences “
 Example :
• Medical imaging system
• Robotics system
• Scientific experiments
• Weapon system
• Home appliances control system
• Phones and cellular switching

2. Types of real time
operating system
Hard real time
operating
system
Soft real time
operating
system

3. Types of Real time operating system (on
the basis of deadline) :
• Hard real time operating system
• Soft real time operating system
 Hard real time operating system :
“This type of operating system can never miss
its deadline. Missing the deadline may have
disastrous consequences is known as hard real
time operating system “
Definition :

4.  Example:
• Flight control systems
• Weapons defense system
• Medical system
• Railway signaling system
Soft real time operating system :
Definition :
“This type of operating system can miss
its deadline occasionally with some
acceptably low probability. Missing
deadline have no disastrous
consequences known as soft real time
operating system.”

5. Example :
• Telephone switches
• Personal computer
• Electronic games
• Weather monitoring systems
Advantages
of (RTOS) :
• Maximum consumption
• Shorter task shifting time
• Best memory allocation
• Quite error free
Disadvantages
of (RTOS):
•Less multitasking
•Complex scheduling algorithm
•Severe consequence on
missing deadline
•Low priority task delay