This chapter provides an overview of microcomputer operating systems— specifically, those commonly found on desktop and laptop computers and the personal mobile devices we use today.
What is an OS? * easier to use, simpler to code, more reliable, more secure... • Look! Infinite memory! Your own private processor! • Multiple concurrent tasks, how does OS decide who gets how much? • fooling the illusionist itself! - what happens during concurrent updates to complex data structures? - what if computer crashes during a block write?
What is an Operating System? “The one program running at all times on the computer” is the kernel. Everything else is either a system program (ships with the operating system) or an application program. A process is a program in execution. It is a unit of work within the system. Program is a passive entity, process is an active entity.
An operating system is an essential component of a computer system. The primary objectives of an operating system is to make computer system convenient to use and utilise
is called the operating system (OS)3, as it is in charge of making sure the system operates correctly and efficiently in an easy-to-use manner. The primary way the OS does this is through a general technique that we call virtualization.
Operating system capabilities and needs depend on: u Needs of applications and usage contexts (from above) u Capabilities and constraints of technology (from below)
Operating System (or shortly OS) primarily provides services for running applications on a computer system. The primary need for the OS arises from the fact that user needs to be provided with services and OS ought to facilitate the provisioning of these services. The central part of a computer system is a processing engine called CPU.