Operating System and Windows
What is an Operating System? An operating system is an organized set or collection of software programs that controls the overall operation of the computer system. The most important program that runs on your computer. It manages all other programs on the machine.
Every PC has to have one program to run other applications or programs. It’s the first thing “loaded�.
Operating System It performs basic tasks such as: •Recognizing input from the keyboard or mouse •Sending output to the monitor
Operating System It also performs the following functions: •Keeping track of files and directories on the disk, and •Controlling peripheral devices such as disk drives and printers.
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.
API , CLI and GUI 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 line Interface (CLI) or a graphical user interface (GUI).
Windows and MAC are GUI’s Microsoft Windows and Apple Macintosh operating systems are “graphical user interfaces” or GUI’s. GUI is defined as: A picture used in place of a word or words to issue commands.
Types of Operating System
Single user
Multi user
1.Single-user This type manages the computer where only one user has access to all the computer resources. 1.Multi-user A multi-user operating System allows for multiple users to have access to same computer resources at the same time.
Operating System can also be described as
Single Tasking
Multi Tasking
Single tasking Each new program runs after the completion of previous one. Multi tasking one or more programs are allowed to run at a time. Multi programming several programs are executed simultaneously at a given time. Multi processing A system capable of supporting and utilizing more than one computer processor.
Functions of an Operating System
Operating systems provide a software platform on top of which other “application� programs can run. (API)
It manages input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports and if any fault occurs it informs the user.
Functions of an Operating System Management of Internal Memory - It manages the sharing of internal memory among multiple applications. Managing Device Drivers Management of CPU time - Where multiple programs are 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 giving another application a turn. Hardware Management- an operating system can ensure that applications continue to run when hardware upgrades and updates occur. Today’s systems can accommodate thousands of different printers, disk drives and special peripherals in any possible combination.
Booting – a wake up call When you turn on the power to a PC, the first program that runs is a set of instructions kept in the computer's read-only memory (ROM).
It checks to make sure everything is functioning properly. It checks the CPU, memory, and basic input-output systems (BIOS) for errors.
Once successful, the software will begin to activate the computer's disk drives. It then finds the first piece of the operating system: the bootstrap loader
The bootstrap loader is a small program that has a single function: It loads the operating system into memory and allows it to begin operation. The Boot strap loader sets up the divisions of • memory • user information, and • applications. Then it turns control of the computer over to the operating system and when it is fully loaded you can see the desktop with icons.
Windows - Desktop