Operating System Support AkhileshShresthacharya Anish Joshi AnishManandhar AshmitaShakya BijayaLaxmi Das
Agenda • Operating System Overview • Objectives of Operating system • Layers of Operating system • Types of Operating System • Scheduling • Memory Management
Operating System Overview • It the software on a computer that manages resources. • Under this software all the other software are being run. • For e.g. Windows7, Linux, Ubuntu etc.
Objectives of Operating System • Convenience: Makes computer more convenient to use. • Efficiency: Allows computer system resources to be used in efficiency. • Ability to evolve: permit effective development testing and introduction of new system function without interfering with services.
Types of Operating System Interactive • Late 1940s and 1950s • Program interacts directly with hardware • Two main problem: • Scheduling • Setup Time
Types of Operating System Batch system • Resident monitor program • Users submit jobs to operator • Operator batches jobs • Monitor controls sequence of events to process batch • When one job is finished, control returns to monitor which reads next jobs • Monitor handles scheduling of jobs
Types of Operating System Single programming (uni- programming) • Only one job in CPU at a time • Next job starts when previous job cycle complete.
Types of Operating System • Multi programming
Scheduling • Scheduling refers to the way processes are assigned to run on the available CPUs. • Types of scheduling: • 1. Long-term scheduler • 2. Mid-term scheduler • 3. Short-term scheduler
Memory Management • Memory management is the act of managing computer memory • This involves providing ways to allocate portions of memory to programs at their request • Types are given on next slide:
Swapping • This swapping is method in which the management of the memory is done by the swapping of memory and Disk storage • It is a process to make the operating system more fast
Partitioning • The simplest scheme for partitioning available memory is to use fixed-size partitions. • Types: • Fixed-size partition • Variable-size partition
Paging • However that memory is partitioned into equal fixed sized chunks of some size. • Then the chunks of a program known as pages could be assigned to available chunks of memory.
Virtual Memory • Virtual memory is a memory management technique developed for multitasking. • If there is only one hardware memory device and this "virtual" device(harddisk) acts like a RAM module.