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About the Presentations
• The presentations cover the objectives found in the
opening of each chapter.
• All chapter objectives are listed in the beginning of
each presentation.
• You may customize the presentations to fit your
class needs.
• Some figures from the chapters are included. A
complete set of images from the book can be found
on the Instructor Resources disc.
Guide to Operating Systems, 5th
Edition
1
Guide to Operating Systems,
th
5 Edition
Chapter 1
Operating Systems
Fundamentals
Objectives
After completing this chapter, you will be able to:
• Explain basic operating system concepts
• Understand the history of operating system
development
• Discuss how operating systems work
• Describe the types of operating systems
• Discuss single tasking versus multitasking
Guide to Operating Systems, 5th Edition
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Objectives
After completing this chapter, you should will be able
to (cont’d):
• Differentiate between single-user and multiuser
operating systems
• List and briefly describe current operating systems
Guide to Operating Systems, 5th Edition
© Cengage Learning 2017
4
An Introduction to Operating Systems
• Computers come in many and varied physical
forms.
• There are:
– Supercomputers that perform complex computing
tasks at incredible speeds;
– Business servers that provide enterprise-level
networked applications;
– Desktop and laptop PCs, tablets , smartphones, and
wearable computers.
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5
An Introduction to Operating Systems
• There are many devices you may not even think of
as having a computer, such as those embedded in
everyday devices like cars, televisions, and even
dishwashers.
• Without an operating system, however, these
devices are only a collection of electronic parts.
• The operating system is the software that starts the
basic functions of a computer, displays documents
on the computer’s monitor, accesses the Internet,
and runs applications.
• It transforms the computer into a powerful tool.
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An Introduction to Operating Systems
• There are many kinds of operating systems, but
only a few have captured a wide audience.
• Server operating systems like Windows Server
2016 and UNIX run on network servers.
• Client operating systems like Windows 10, Mac OS
X, and Ubuntu Linux run on desktop computers.
• Sime operating systems are very specialized and
rarely seen, such as those that run the electronics
in a car.
• Others are ubiquitous, such as Android and iOS,
which run mobile devices.
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An Introduction to Operating Systems
• A computer’s functions and features can be broken
down into three basic tasks all computers perform:
– Input
– Processing
– Output
• These functions above involve some type of
computer hardware
– But the hardware is controlled and coordinated by
the operating system (OS)
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An Introduction to Operating Systems
• An OS is a specialized computer program that
provides the following features:
– User interface – provides a method for users to
interact with the computer
– File system – method by which an OS stores and
organizes files and manages access to files
– Processes and services – a process is a program
that’s loaded into memory and run by the CPU; a
service is a type of process that runs in the
background because there’s no user interface.
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An Introduction to Operating Systems
• An OS is a specialized computer program that
provides the following features:
– Kernel – the heart of the OS and runs with the
highest priority.
• It schedules processes to run, making sure highpriorities are taken care of first;
• It manages memory to ensure that two applications
don’t attempt to use the same memory space;
• It makes sure I/O devices are accessed by only one
process at a time, in addition to other tasks.
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Desktop Versus Server Operating
System
• Two types of OSs will be covered in this book:
– Desktop operating system (client OS) – installed on
a personal computer (PC) that is used by one
person at a time, and may be connected to a
network
• Examples of installations are desktop computers,
laptops, iMac computers, and tablets
– Server operating system – installed on a more
powerful computer that is connected to a network
and enables multiple users to access information
such as e-mail, files, and software
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Desktop Versus Server Operating
System
• Traditional server – often used by small or medium
businesses
• Rack-mounted server – CPU boxes mounted in
racks that can hold multiple servers
– All servers often share one monitor & pointing device
• Blade servers – looks like a card that fits into a
blade enclosure
– A blade enclosure is a large box with slots for blade
servers
– Medium and large organizations use blade servers
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Input and Output
• A basic task of an OS is to take care of input/output
(I/O) functions, which let other programs
communicate with the computer hardware
• Some examples of I/O tasks:
– Handle input from the keyboard, mouse, and other
input devices
– Handle output to the monitor and printer
– Manage network communications, such as for a
local network and the Internet
– Control input/output for devices such as network
interface card
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Input and Output
• Some examples of I/O tasks (cont’d):
– Control information storage and retrieval using
various types of disk
– Enable multimedia use for voice and video
composition or reproduction, such as recording
video from a camera or playing music
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Input and Output
Figure 1-1 General tasks for all operating systems
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A Short History of Operating Systems
• Initially, computers were used as large automated
calculators for mathematical and statistical
problems
• Legitimate use can be traced back 100 years or
more but there were no practical designs used by
significant numbers of people until the late 1950’s
• Operating systems were rudimentary, often not
able to do more than read punch cards or tape and
write output to machines resembling typewriters
– It did not take long before applications evolved to do
something useful for a broader audience
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A Short History of Operating Systems
• Computers of the late 60’s and early 70’s were
crude by today’s standards but were quite capable
– Contributed to the development of space travel,
submarine-based ballistic missiles, and a growing
global financial community
• This period saw:
– The beginning of the Internet
– Creation of input and output devices such as display
terminals and magnetic disks
– Creation of more operating systems such as OS/8
and UNIX
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A Short History of Operating Systems
• PDP-8 computers were general-purpose machines
that at one time were the top-selling computers
across the world.
• The PDP series could also run Multics, which was
the basis for the development of the first version of
UNIX, a multi-user, multitasking operating system.
– Multics is widely considered to be the first multiuser,
multitasking operating system.
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A Short History of Operating Systems
• The original UNIX was developed at AT&T Bell
Labs in 1969 by Kenneth Thompson and Dennis
Ritche as an improvement on Multics.
• DEC VAX computers used Virtual Memory System
(VMS), a powerful, multitasking, multiuser
operating system that was strong on networking.
• IBM mainframes made a series of operating
systems popular in the early sixties and later with
System/360, including CICS, which is still in use
today.
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A Short History of Operating Systems
• In the mid-1960’s, a simple programming language
was developed at Dartmouth College
– BASIC – Beginner’s All-purpose Symbolic Instruction
Code
• In 1975, Bill Gates wrote a compiler (software that
turns computer code written by people into code
that is understood by computers) for BASIC
– Sold it to a company called Micro Instrumentation
Telemetry Systems (MITS) who became the first
company to produce a desktop computer.
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A Short History of Operating Systems
• Other programming languages introduced around this
time included Pascal, C, and other versions of BASIC.
• Bill Gates started a new company called Microsoft.
• This led to the development of popular mainframe and
minicomputer programming languages, such as
FORTRAN and COBOL.
• The microcomputers, introduced in the mid-1970s, had
many of the old restrictions, including slow speed and
little memory, and came with a small operating system.
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A Short History of Operating Systems
• Gates put together a team at Microsoft to adapt a
fledging version of a new microcomputer operating
system called 86-DOS which ran on a new
microcomputer being developed by IBM called the
personal computer.
• 86-DOS evolved in 1980 into the Microsoft Disk
Operating System or MS-DOS.
– MS-DOS was designed as a command-line interface –
users typed in commands instead of using the graphical
user interface (GUI) point-and-clock method that is
common today.
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A Short History of Operating Systems
– MS-DOS became a runaway success for Microsoft, and it
was the first widely distributed operating system for
microcomputers that had to be loaded from disk or tape
– IBM adopted MS-DOS for its PC
• MS-DOS:
– Provided the basic operating system functions and it was
amazingly similar to what was used before on larger
computers.
– It supported basic functions, such as keyboard, disk, and
printer I/O – and communications.
– In time it added added support for hard disks.
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A Short History of Operating Systems
• In 1984, Apple Macintosh developed a GUI and mouse
pointing device, which allowed users to interact with the
OS on a graphical screen.
• The mouse allowed users to point at or click icons or to
select items from menus to accomplish tasks.
• When the Macintosh was introduced, it seemed light
years ahead of the IBM-PC.
• Its OS came with a standard GUI at a time when MSDOS was still based on entering text commands.
• The Macintosh OS managed computer memory closely
for the software – which MS-DOS did not do.
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A Short History of Operating Systems
• Because Mac OS managed all computer memory for
the application programs, you could start several
programs and switch among them.
• Mac OS was also years ahead in I/O functions such as
printer management.
– In MS-DOS, a program had to provide its own drivers for
I/O devices. MS-DOS provided only the most rudimentary
interface.
• On Mac OS, many I/O functions were part of the
operating system.
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A Short History of Operating Systems
• In 1985, Microsoft shipped an extension to its DOS OS,
called Microsoft Windows, which provided a GUI and
many of the same functions as MAC OS.
• The first Windows was really an operating
“environment” running on top of MS-DOS, made to look
like a single OS.
• Today’s Windows is no longer based on DOS and is a
full-fledged OS.
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A Short History of Operating Systems
• All of these PC operating systems changed the role
of the big machines’ dynasty.
• Many big machines are now obsolete.
• Others are used for calculation and data storage as
back-end functions for the PC.
• Even in this arena, they are threatened today as
PC operating systems and hardware extend further
and further.
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Understanding How Operating
Systems Work
• Elements that enable an operating system to work
with a computer include:
–
–
–
–
–
The kernel
Resource managers
Device drivers
Application software
BIOS
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The Kernel
• The kernel consists of the essential program code
of the operating system.
• Key tasks of the OS Kernel:
– Scheduling computer processes
– Managing resources, such as memory and processing
time
• Jobs performed by the kernel can include:
– Managing interactions with the CPU
– Starting, managing, and scheduling programs that
handle I/O activities, including device and
networking activities
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The Kernel
• Jobs performed by the kernel (cont’d):
– Handling basic computer security
– Managing use of the computer’s memory (RAM)
– Managing priority levels assigned to programs and
computer processes
• In Windows systems, the name of the kernel file is
ntoskrnl.exe and in MAC OS X, the kernel is called
XNU.
• The actual kernel name in Linux depends on the
distribution and release of Linux.
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Resource Managers
• Help ensure memory is used properly and there
are no memory conflicts
• Manages how programs access the processing
capabilities of the CPU
– Example: if there is one CPU and ten programs that
want to access the CPU, the OS will give each
program a time slice on the CPU
• Each program does a little work during its time slice
and then the kernel hands the CPU access over to the
next program for its time slice
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Device Drivers and the Operating
System
• A device driver translates computer code to display
text on a screen
– Or translates movements of a mouse into action
• A separate device driver is usually present for each
I/O device
• The device driver contains the actual code
(instructions) to communicate with the chips on the
device
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Device Drivers and the Operating
System
Figure 1-2 Device drivers provide communication between the OS and hardware devices
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The Role of Application Software
• Application software
– Any program a user might choose to run on a
computer
• Examples: word processor, spreadsheet, database,
and a computer game
• An operating system manages the communication
among the applications, the user, and the computer
– Allows application programmers to concentrate on
applications that will run on any hardware, as long
as the OS can control them
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The Role of Application Software
Figure 1-3 Application programs communicate with hardware through the operating system
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The Role of Application Software
• An operating system manages the communication
among the application programs, the user, and the
computer.
• An application program can submit a general
request to the OS, such as “write this information to
disk,” and the OS handles the details.
• The application program doesn’t have to worry
about how to queue data, update the disk directory,
or physically copy data from memory to the hard
drive.
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The Role of the BIOS
• BIOS – basic input/output system
• A low-level program code that:
– Resides on a chip on the computer’s motherboard
– Initiates/enables communications with hardware
devices
– Performs tests at startup called power-on self test
(POST)
– Conducts basic hardware and software
communications inside the computer
– Starts a full-fledged operating system that interfaces
with the user
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The Role of the BIOS
• Every PC has a BIOS, which is stored in a flash
memory chip
– Flash memory does not lose its contents when the
computer is turned off
• BIOS is stored in a complementary metal oxide
semiconductor (CMOS) memory chip
• When a PC is turned on:
– Runs a startup program inside the BIOS
– Program initializes the screen and keyboard, tests
hardware, initializes the hard disk and other drives
– Loads the main operating system from the hard disk
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A Summary of Operating System
Elements
Figure 1-5 General operating system design
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Types of Operating Systems
• Operating systems are organized by the size, type,
and purpose of the computer on which they run
– Example: PC-class computers are designed for
individual users to perform tasks, such as word
processing, spreadsheet management, and
networking with other computers
• Early operating systems were written for large,
refrigerator-sized machines and were quite
complex
– Applications were written with efficient code and
appearance was very basic
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Types of Operating Systems
• Today, “big” machines no longer refer to size
– Refers to more processing power, more memory,
more storage, and better network connectivity
• To operate today’s more powerful computers, more
powerful and more capable operating systems are
needed.
• Today’s operating systems must support:
– Multitasking
– High-speed network applications
– More powerful I/O capabilities
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Types of Operating Systems
• Factors that differentiate high-end and low-end
computers:
– Speed of disk controller, size and speed of the hard
disk, amount and speed of memory, size of data
pathways, or speed and number of CPUs
• Computers and operating systems can be looked at in
terms of one or more of the following characteristics:
– Time sharing
– Real time
– Multiuser
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Time Sharing
• A time-sharing system is a central computer
system that is used by multiple users and
applications simultaneously
– Mainframe computers are an example
– Used to perform massive calculations or manipulate
huge amounts of data (batch processing)
• Example: clearing two million checks and updating
their associated bank accounts in batches
– Sequential processing: used by smaller computers
where each process request is completed, and the
data returned before the next process is started
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Time Sharing
• Besides batch processing, many clerks, customer
representatives, and ATM machines often use a
mainframe to do daily transactions.
• They all share the resources, or processor time, of
the large machine, which is why such machines are
called time-sharing systems.
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Time Sharing
Figure 1-6 Time-sharing mainframe with terminals
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Real-Time Systems
• A real-time operating system (RTOS) receives and
processes inputs and produces the required
outputs in a specified amount of time
– Example: might be used in an industrial plant to
control machinery
– Might be used in an industrial plant to control
machinery.
– Inputs to the computer controlling the machinery
dictate how the machines respond.
– The response must be consistent and predictable, or
the entire process may be thrown off.
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Real-Time Systems
• These OSs are typically used in embedded
systems
– The computer has a dedicated function within a
larger system such as a piece of machinery.
– Examples of embedded systems include the
computer that runs all the systems of a modern
automobile or the computers that run the robots on
an automated assembly line.
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Multiuser Systems
• A multiuser system supports multiple users who
access the hardware and software of the computer
and operating system
– Both time-sharing and real-time systems can be
multiuser
– All of the work is typically done on the big machine,
including running programs, storing data, and
accessing data.
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Multiuser Systems
• Client/server systems – only some of the work is
done on the central computer (server)
– The servers may hold all the data and files, and may
even perform some of the database functions or
calculations required.
– Most of the work, such as running programs, is
performed on the client side
• Client/server computing was not possible until the
PC was introduced
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Multiuser Systems
• Cloud computing: providing scalable Web-based
applications and services over the Internet or a
private network that are used by clients through
Web browsers or specialized apps.
• The servers and resources available through the
apps are depicted as available in a cloud because
there are many resources, but they appear to be
available from one unified resource.
• In cloud computing, the user experiences programs
and data as if they are installed on the user’s
computer, but a small portion is on the local
computer and all other resources are on servers
and other devices in the cloud.
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Multiuser Systems
• Microsoft describes three types of cloud models:
– Private cloud – computing resources are kept within
an organization and used exclusively by that
organization.
– Hosted private cloud – resources are made available
through a third-party outsourcer, but are only
accessible to users within a specific organization.
– Public cloud – a variety of resources are available to
any organization through a third party and each
organization subscribes only to specific resources,
which may be shared by other organizations.
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Multiuser Systems
Figure 1-8 Cloud computing
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Multiuser Systems
• Common cloud service providers include:
– Amazon Web Services (AWS)
– Microsoft Azure
– Dropbox
• AWS and Microsoft Azure are full-service cloud
computing companies that can offer customers
anything from cloud storage to an entire network of
servers and services.
• Dropbox is a cloud storage company that provides
seamless access to files through the Internet.
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Single Tasking Versus Multitasking
• Earlier versions of OSs allowed programs to
directly access hardware
– More prone to unexpected hangs, system instability,
or crashes
• Today’s OSs manage access to hardware
– Major reason for this was to facilitate multitasking
(running two or more programs at the same time)
• Two general types of multitasking:
– Cooperative multitasking
– Preemptive multitasking
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Single Tasking Versus Multitasking
• Cooperative multitasking – the OS hands over
control to a program and then waits for the program
to hand control back to OS
– If program does not give control back to OS, it may
hog the CPU until its operations are complete
– No other program can run until control is given back
to OS
– Found in early Windows versions
– Example: If you print a word-processing file and try
to play Solitaire, you cannot play a card until the
print job is finished
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Single Tasking Versus Multitasking
Figure 1-9 Cooperative multitasking basics
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Single Tasking Versus Multitasking
• Preemptive multitasking – the OS is in control of
the computer at all times
– Lets programs execute a little of code at a time then
forces the program to relinquish control of the CPU
– OS has control over how much of the computer’s
resources are allocated to each program
– Computers must use more of its CPU and memory
to support the OS, but the behavior of the computer
is more predictable
– You could play Solitaire while printing a wordprocessing file
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Single Tasking Versus Multitasking
Figure 1-10 Preemptive multitasking basics
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Single Tasking Versus Multitasking
• Single-tasking operating systems – execute one
program at a time
– To do something else, one program must be
stopped
– Older OSs like MS-DOS were single-tasking
Figure 1-11 Single-tasking operating systems
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Single Tasking Versus Multitasking
• Task-switching operating systems – more than one
program can run at a time but only one program
can have control at a time
– Earlier versions of Mac OS were task-switching
Figure 1-12 Task switching
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Single-User Versus Multiuser
Operating Systems
Table 1-3 Comparing single-user and multiuser operating systems
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Current Operating Systems
• OS covered in this book:
–
–
–
–
Windows 7, 8.1, and 10
Windows Server 2008, 2012, and 2016
UNIX/Linux distributions
Apple Macintosh MAC OS X (version 10.11 El
Capitan)
• Chapter 2 covers these OSs in more detail
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Summary
• All computers perform three basic tasks: input,
processing, and output
• An operating system provides the foundation upon
which to run the components of a computer and
execute applications
• A basic task of an operating system is to enable a
computer to perform I/O functions
• Two common types of operating systems are
desktop and server operating systems
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Summary
• The history of operating systems and computers
represents a progression from huge computers to
large computers to desktop-sized computers that
have powerful operating systems
• Device drivers can extend the native function of an
operating system to provide access and control
over different types of devices
• The BIOS is a low-level program code that
operates between the computer hardware and an
operating system to initiate communication with
hardware devices
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Summary
• An OS may be geared to run a large mainframe or
a small PC-type of computer
• OSs can be understood in terms of characteristics
such as time sharing, real-time operation, and
multiuser capabilities
• One of the most significant advances in operating
systems is the refinement of the GUI in Windowsbased and Mac OS systems
• Early OSs tended to be single-tasking, but
modern systems are largely multitasking
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Summary
• A true multiuser system is one in which multiple
users access and run a single application on a
single computer at the same time
• Currently popular OSs are the topic of this book
and include Windows 7, 8.1, and 10, Server
2008/R2, Server 2012/R2, Server 2016,
UNIX/Linux, and Mac OS X El Capitan
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