OS1: Process Management – Unit 1: Processes

Early computer systems allowed one program to be executed at a time. This program has complete control of the system, and had access to all the system’s resources. Current-day computer systems allow multiple programs to be loaded into memory and to be executed concurrently. This evolution requires firmer control and more compartmentalization of the various programs. These needs resulted in the not ion of a process, which is a program in execution. A process is the unit of work in a modern time-sharing system. Although, the main concern of the OS is the execution of user programs, it also needs to take care of various system tasks that are better left outside the kernel itself. A system therefore consists of a collection of processes: Operating system processes executing system code, and user processes executing user code. All these processes can potentially execute concurrently, with the CPU (or CPUs) multiplexed among them. By switching the CPU between processes, the operating system can make the computer more productive. 2.0 Objectives At the end of this unit, you should be able to: Define a process List the possible states of a process Describe a process control block (PCB) Describe process creation and process termination