1.Introduction To Operating System

A program that acts as an intermediary between a user and the computer hardware

An operating system, or OS, is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer would be useless

Operating systems can also be considered to be managers of the resources. An operating system determines which computer resources will be utilized for solving which problem and the order in which they will be used

Software controlling the overall operation of a multipurpose computer system, including such tasks as memory allocation, input and output distribution, interrupt processing, and job scheduling

1.1 Understand Terms and Concepts of Operating System

Batch Systems: No User Interaction

Batch System
Multi-Programming: Multiple Programs Loaded in Memory

Multi-Programming
Time-sharing: each process receives slices of CPU time

Time Sharing
Interactive systems: provides quick response to user’s actions

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Multi-user: distinction between users

Multi User
Network OS: users aware of the existence of multiple computers

Network
Distributed OS: looks like a traditional single-processor system

Distributed
Processes, Files, System Calls

File

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3.1.1 Identify Between Resident And Transient Routines

Memory Management Memory management is concerned with managing: The computer’s available pool of memory Allocating space to application routines and making sure that they do not interfere with each other. 3.1.1 Identify between resident and transient routines The operating system is a collection of software routines. Resident routines Transient routines Routines that directly support application programs as they run Stored on disk and read into memory only when needed Example: routine that control physical I/O Example: routine that formats disks The operating system occupies low memory beginning with address 0. Key control information comes first followed by the various resident operating system routines. The remaining memory, called the transient area, is where application programs and transient operating system routines are loaded. Resident & transient routines structure...

Operating Systems Definition and the Classification of OS

OPERATING SYSTEMS ( OS ) What is an operating system? An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI). An operating system performs these services for applications: In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before g...

2.1.4 Distinguish between logical I/O and physical I/O

2.1.4 Distinguish between logical I/O and physical I/O logical input relate to hard disk Logical I/O an Physical I/O Physical" I/O is an actual fetch of data from a storage device such as a disk. Logical" I/O is a programmatic request for data satisfied by a memory (block, buffer) access. A logical I/O may cause a physical I/O in the first place, or a logical I/O may retrieve a part of a block (buffer) of data from memory. 2.1.5 Distinguish between directory management and disk space management. Directory management A directory is a hierarchical collection of directories and files. The only constraint on the number of files that can be contained in a single directory is the physical size of the disk on which the directory is located. Disk management A hard disk is a rigid disk inside a computer that stores and provides relatively quick access to large amounts of data. It is the type of storage most often used with Windows. The system also supp...

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