Operating System Subject Overview (ICT Night Class)

By Aurelie A. Peralta

Let me give you insights on the main topics that we are going to discuss in this subject.

For the first three chapters, we will explain what operating systems are, what they do, and how they are designed and constructed. We will discuss how the concept of an operating system has developed, what the common features of an operating system are, what an operating system does for the user, and what it does for the computer-system operator. These chapters serve as the OVERVIEW for the whole course.

Next is PROCESS MANAGEMENT, we will describe here the process concept and concurrency as the heart of modern operating systems. A process is the unit of work in a system. Such a system consists of a collection of concurrently executing processes, some of which are operating-system processes (those that execute system code), and the rest of which are user processes (those that execute user code).

In STORAGE MANAGEMENT, we will discuss processes in main memory during execution. To improve both the utilization of CPU and the speed of its response to its users, the computer must keep several processes in memory. We will discuss also different memory-management schemes.

We will describe the devices that attach to a computer and the multiple dimensions in which they vary under I/O SYSTEMS. In many ways, they are also the slowest major components of the computer. Because devices differ so widely, the operating system needs to provide a wide range of functionality to applications to allow them to control all aspects of the devices.

DISTRIBUTED SYSTEMS deal with a collection of processors that do not share memory or a clock - a distributed system. Such a system provides the user with access to the various resources that the system maintains. Access to a shared resource allows computation speedup and improved data availability and reliability. Such a system also provides the user with a distributed file system, which is a file-service system whose users, servers, and storage devices are dispersed among the sites of a distributed system.

And lastly, PROTECTION AND SECURITY, wherein we will explain the processes in an operating system that must be protected from one another’s activities. For the purposes of protection and security, we use mechanisms that ensure that only those processes that have gained proper authorization from the operating system can operate on the files, memory segments, CPU, and other resources. Protection is a mechanism for controlling the access of programs, processes, or users to the resources defined by a computer system. This mechanism must provide a means for specification of the controls to be imposed, as well as a means of enforcement. Security protects the information stored in the system (both data and code), as well as the physical resources of the computer system, from unauthorized access, malicious destruction or alteration, and accidental introduction of inconsistency.

Reference: Operating System Concepts by Silberschatz, Galvin, and Gagne, 2003