Real time operating system
- 1. Real-time Operating System UNIT 1Prepared by: Sahil B. Mulani Guided by: Mrs. Minal Zope All India Shree Shivaji Memorial Society’s Institute of info. Technology Pune -01
- 2. Contents: 1. Operating Systems Concepts 2. Real-Time Tasks 3. Real-Time Systems 4. Types of Real Time Tasks 5. Real-Time Operating Systems
- 3. Operating Systems Concepts: • An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. • An operating system is a program that acts as an interface between the user and the computer hardware and controls the execution of all kind of programs.
- 4. Functions of an operating System: • Memory Management • Processor Management • Device Management • File Management • Security • Control over system performance • Job accounting • Error detecting aids • Coordination between other software and users
- 5. Memory Management: • Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address. • Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory.
- 6. Processor Management In multiprogramming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. An Operating System does the following activities for processor management − Keeps tracks of processor and status of process. The program responsible for this task is known as traffic controller. Allocates the processor (CPU) to a process. De-allocates processor when a process is no longer required.
- 7. Device Management An Operating System manages device communication via their respective drivers. It does the following activities for device management − Keeps tracks of all devices. Program responsible for this task is known as the I/O controller. Decides which process gets the device when and for how much time. Allocates the device in the efficient way. De-allocates devices.
- 8. File Management A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions. An Operating System does the following activities for file management − Keeps track of information, location, uses, status etc. The collective facilities are often known as file system. Decides who gets the resources. Allocates the resources. De-allocates the resources.
- 9. Other Important Activities Following are some of the important activities that an Operating System performs − Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data. Control over system performance − Recording delays between request for a service and response from the system. Job accounting − Keeping track of time and resources used by various jobs and users. Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids. Coordination between other software and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.
- 10. Real time operating systems • Definition – Systems whose correctness depends on their temporal aspects as well as their functional aspects • Performance measure – Timeliness on timing constraints (deadlines) – Speed/average case performance are less significant. – Performance can be measured in terms of time • Key property – Predictability on timing constraints
- 11. Real-Time System operating Example Digital control systems periodically performs the following job: 1. senses the system status and 2. actuates the system according to its current status Control-Law Computation Sensor Actuator
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