The document discusses the four main operating systems - Linux, Mac, Unix, and Windows. It explains that all operating systems are based on four management areas: the device manager, file manager, memory manager, and process manager. The device manager monitors devices and allocates resources. The file manager checks file types and permissions. The memory manager manages RAM allocation. And the process manager decides how to allocate the CPU and tracks process status.

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The Four Main Operating Systems
By Liz Ristau

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What is an operating system?
 An operating system is the chief program that
manages all of the hardware and software, it has
control of every process, every file, every
section of memory and device.
 Acts like the middle man.
 Makes sure that the hardware and the software
are interacting correctly.
 The main four are Linux, Mac, Unix and
Windows.

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Similar Concept
 All four of the operating systems are based off of
four management areas, in which the operating
system is seen as the boss that oversees the
interactions between the four management
areas.
 The four management areas are device
manager, file manager, process manager and,
memory manager; which all interact as a team in
order to get the job done.

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The Device Manager
 Monitors every device channel and control unit.
 Must decide which way to allocate all the
systems that are connected to the computer.

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The File Manager
 Checks every type of file that is on the system;
data files, program files, compilers and installed
applications.
 This manager helps users set permission so that
certain users can only see certain files; just like
our school computers or your parents
computers, when a guest logs in your parents
are not going to want guests to see their
personal information, programs and, files.

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The Memory Manager
 Is in charge of the main memory; RAM.
 It scans everything in the memory for the new
request, in order to make sure the information is
valid.
 Allows for allocation of the room that is not
already taken up.
 The memory spaces may need to be de-
allocated at times, in order to free up spaces for
new request.

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The Process Manager
 Decides how to allocate the brain of the
computer.
 Aka the central processing unit.
 Must keep track of the status of each process as
it has to handle the jobs as they enter the
system along with the process that is associated
with each of those jobs.

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The other manager:
The Network Manager
 This allows for users to share hardware and
software resources while controlling the users
access to them.

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Us Users
 We rely upon the interface, which gives us a
visual understanding of what we are trying to do
while interacting with the system.
 For example, when dragging a file into a folder,
you are physically (not literally) seeing the file
moving into that folder.