2014329620008_张昱_homework1 (28.218.81608.81609.81613.222.81848.81855)

A user may be able to run several programs at one time:a word processor,a web browser,and an e-mail package.Even if the user can execute only one program at a time,the operating system may need to support its own internal programmed activities,such as memory management.In many respects,all these activities are similar,so we call all of them processes.