A computer is an electronic device that manipulate information , or data. It has the ability to store, retrieve, and process data. You can use a computer to a type documents, send email, and browse the Web. You can also use it to handle spreadsheets, accounting, database management, presentations, games and more.
- A file is a collected of related information defined by its creator. Computer can store files on the disk, which provide long term storage. A file system normally organized into directories to ease their use. These directories may contain files and other directions.
The five main major activities of an operating system with regard to file management are :
- The creation and D deletion of files.
- The creation and deletion of directions
- The support of primitives for manipulating files and directions.
- The mapping of files onto secondary storage.
- The backup of files on stable storage media.
- Primary-Memory or Main-Memory is a large array of words or bytes. Each word or byte has its own address. Main-memory provides storage that can be access directly by the CPU. That is to say for a program to be executed, it must be in the main memory.
The major activities of an operating in regard to memory-management are:
- Keep track of which part of memory are currently being used and by whom.
- Decide which process is loaded into memory when memory space becomes available.
- Allocate and de allocate memory space as needed.
- The operating system manages many kinds of activities ranging from user programs to system programs like printer spooler, name servers, file server etc. Each of these activities is encapsulated in a process. A process includes the complete execution context.
The five major activities of an operating system in regard to process management are as under:
- Creation and deletion of user and system processes.
- Suspension and resumption of processes.
- A mechanism for process synchronization
- A mechanism for process communication.
- A mechanism for deadlock handling.
The core of the operating system is the kernal, a control program that functions in privileged state, reacting to interrupts from external devices and to service requests and traps from processes. Generally, the kernel is a permanent resident of the computer. It creates and terminates processes and responds to their request for service.
An operating system is the set of programs that controls a computer. Some examples of operating systems are UNIX, MS-DOS,MS-Windows, Windows/NT, OS/2,MacOSi9,VMS,MVS, and VM.