OPERATING SYSTEMS

Operating Systems

TABLE OF CONTENT

INTRODUCTION3

HISTORY OF OPERATING SYSTEM4

The 1940's - First Generations4

The 1950's - Second Generation4

The 1960's - Third Generation5

Fourth Generation6

DISCUSSION7

SYSTEM COMPONENTS7

Process Management7

Main-Memory Management8

File Management9

I/O System Management9

Secondary-Storage Management10

Networking11

Protection System11

Command Interpreter System11

MULTIPROGRAMMED BATCH SYSTEMS12

FUNCTIONS OF AN OPERATING SYSTEM13

JOB MANAGEMENT AND PROTECTION14

Userland Security15

CONCLUSION16

REFERENCES17

Operating Systems

Introduction

The 1960's definition of an operating system is “the software that controls the hardware”. However, today, due to microcode we need a better definition. We see an operating system as the programs that make the hardware useable. In brief, an operating system is the set of programs that controls a computer. Some examples of operating systems are UNIX, Mach, MS-DOS, MS-Windows, Windows/NT, Chicago, OS/2, MacOS, VMS, MVS, and VM.

Controlling the computer involves software at several levels. We will differentiate kernel services, library services, and application-level services, all of which are part of the operating system (Finkel 2000). Processes run Applications, which are linked together with libraries that perform standard services. The kernel supports the processes by providing a path to the peripheral devices. The kernel responds to service calls from the processes and interrupts from the devices. The core of the operating system is the kernel (Lane and Mooney 2003), a control program that functions in privileged state (an execution context that allows all hardware instructions to be executed), 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 (Tanenbaum 2003).

History of operating system

Historically operating systems have been tightly related to the computer architecture, it is good idea to study the history of operating systems from the architecture of the computers on which they run. Operating systems have evolved through a number of distinct phases or generations which corresponds roughly to the decades (Stallings 2001).

The 1940's - First Generations

The earliest electronic digital computers had no operating systems. Machines of the time were so primitive that programs were often entered one bit at time on rows of mechanical switches (plug boards) (Silberschatz and Peterson 2000). Programming languages were unknown (not even assembly languages). Operating systems were unheard of .

The 1950's - Second Generation

By the early 1950's, the routine had improved somewhat with the introduction of punch cards (Milenkovic 2001). The General Motors Research Laboratories implemented the first operating systems in early 1950's for their IBM 701. The system of the 50's generally ran one job at a time. These were called single-stream batch processing systems because programs and data were submitted in groups or batches (Dietel 2003).

The 1960's - Third Generation

The systems of the 1960's were also batch processing systems, but they were able to take better advantage of the computer's resources by running several jobs at once. So operating systems designers developed the concept of multiprogramming in which several jobs are in main memory at once; a processor is switched from job to job as needed to keep several jobs advancing while keeping the peripheral devices in use (Stallings ...