An operating system (OS) is essential software that facilitates communication between computer hardware and software, making computers functional. Various types of operating systems include single-user, multi-user, multitasking, and real-time operating systems, each designed for different user needs and functionalities. Examples of popular OS include Microsoft's Windows and Apple's macOS, while real-time systems like QNX are used for controlling machinery and industrial applications.

1.  An operating system or OS is a software
program that enables the
computer hardware to communicate and
operate with the computer software. Without a
computer operating system, a computer and
software programs would be useless. The
picture is an example of MicrosoftWindows
XP,
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3. Distinguished by the response time and how data is
entered into the system
 Single user
 Multi user
 Multitasking
 Multi processing /parallel system
 Distributed
 Real time(RTOS)
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4. TWO TYPES:
 Single user, single task
 Single user, multi tasking
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5.  Designed to manage the computer so that
one user can effectively do one thing at a
time.
 Example: The Palm OS for Palm
handheld computers
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6.  Designed with a single user in mind but can deal with many
applications running at the same time
 Type of operating system
most people use on
their desktop and
laptop computers today
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7.  Examples: Microsoft's Windows and Apple's Mac
OS platforms
 For Example: It's entirely possible for a
Windows user to be writing a note in a word
processor while downloading a file from the
Internet while printing the text of an e-mail
message.
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9.  Allows many different users to take advantage of
the computer's resources simultaneously
 Allows multiple users to access the computer
system at the same time
 Time Sharing system and Internet servers as the
multi user systems
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10.  Examples: UNIX, VMS and Mainframe
Operating systems
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11.  Allows more than one program to run concurrently.
 The tasks share common processing resources, such as a CPU and
main memory
 In the process, only one CPU is involved, but it switches from one
program to another so quickly that it gives the appearance of
executing all the programs at the same time.
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13.  Multiprocessing, in general, refers to the utilization of
multiple CPUs in a single computer system
 Enables several programs
to run concurrently
 The term also refers to the
ability of a system to support
more than one processor
and/or the ability to allocate
tasks between them
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14.  The OS defines a job which has predefined sequence of commands,
programs and data as a single unit.
 The OS keeps a number a jobs in memory and executes them without any
manual information.
 Jobs are processed in the order of submission, i.e., first come first served
fashion.
 When a job completes its execution, its memory is released and the output
for the job gets copied into an output spool for later printing or processing.
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16.  is a multitasking operating system that aims at executing real-time
applications
 The main objective of real-time operating systems is their quick and
predictable response to events
 In it, the time interval required to process and respond to inputs is so
small that it controls the environment
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17.  Examples: QNX, RTLINUX
 Are used to control machinery, scientific instruments and
industrial systems
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