Introduction

Early operating systems allow only one program to be executed. Modern operating systems allow more than one program to be executed simultaneously. The operating system has to offer different facilities to be able to run several programs simultaneously. The operating system has to be able to schedule these programs. The operating system has to be able to apply different operations on the processes. The running processes have to be able to communicate with each other. Finally, the concept of threads will be studied which is supported by modern operating systems.