INTRODUCTION TO COMPUTERS,PROGRAMS, AND JAVA - Introduction to Java Programming: Comprehensive Version - page 10

1.4.1 Controlling and Monitoring System Activities
Operating systems perform basic tasks, such as recognizing input from the keyboard, sending
output to the monitor, keeping track of files and folders on storage devices, and controlling
peripheral devices, such as disk drives and printers. An operating system must also ensure
that different programs and users working at the same time do not interfere with each other.
In addition, the OS is responsible for security, ensuring that unauthorized users and programs
are not allowed to access the system.

1.4.2 Allocating and Assigning System Resources
The operating system is responsible for determining what computer resources a program
needs (such as CPU time, memory space, disks, input and output devices) and for allocating
and assigning them to run the program.

1.4.3 Scheduling Operations
The OS is responsible for scheduling programs' activities to make efficient use of system
resources. Many of today's operating systems support techniques such as multiprogramming ,
multithreading , and multiprocessing to increase system performance.
Multiprogramming allows multiple programs to run simultaneously by sharing the same
CPU. The CPU is much faster than the computer's other components. As a result, it is idle
most of the time—for example, while waiting for data to be transferred from a disk or waiting
for other system resources to respond. A multiprogramming OS takes advantage of this
situation by allowing multiple programs to use the CPU when it would otherwise be idle. For
example, multiprogramming enables you to use a word processor to edit a file at the same time
as your Web browser is downloading a file.
Multithreading allows a single program to execute multiple tasks at the same time. For
instance, a word-processing program allows users to simultaneously edit text and save it to a
disk. In this example, editing and saving are two tasks within the same application. These two
tasks may run concurrently.
Multiprocessing , or parallel processing , uses two or more processors together to per-
form subtasks concurrently and then combine solutions of the subtasks to obtain a solution
for the entire task. It is like a surgical operation where several doctors work together on
one patient.

multiprogramming

multithreading

multiprocessing

1.18

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What is an operating system? List some popular operating systems.

Check

1.19

Point

What are the major responsibilities of an operating system?

1.20

What are multiprogramming, multithreading, and multiprocessing?

1.5 Java, the World Wide Web, and Beyond
Java is a powerful and versatile programming language for developing software
running on mobile devices, desktop computers, and servers.

Key
Point

This topic introduces Java programming. Java was developed by a team led by James Gosling
at Sun Microsystems. Sun Microsystems was purchased by Oracle in 2010. Originally called
Oak, Java was designed in 1991 for use in embedded chips in consumer electronic appliances.
In 1995, renamed Java , it was redesigned for developing Web applications. For the history of
Java, see www.java.com/en/javahistory/index.jsp .
Java has become enormously popular. Its rapid rise and wide acceptance can be traced
to its design characteristics, particularly its promise that you can write a program once
and run it anywhere. As stated by its designer, Java is simple , object oriented , distributed ,