An operating system acts as an intermediary between the user and computer hardware, managing processes, memory, devices, and errors. It determines which applications run and for how long, shares memory among apps, controls I/O, and divides programs across processors. The main purposes of an OS are providing convenience by controlling hardware and resources, efficiency by managing data movement and storage, and adaptability by allowing testing, development and changes.

1. The Basics

2. An operating system
(OS) acts as a
mediator between
the user and the
computer’s
hardware.
It may be helpful to think of the
OS as a translator between you
and your computer.

3. • Tasks:
• Determines which
applications should run in
what order and for how long
(multitasking)
• Manages sharing of internal
memory (RAM) among
multiple applications
• Manages I/O from attached
hardware devices
• Sends messages about the
status of operation, as well
as any errors that may have
occurred
• Manages how to divide
program so that it runs on
multiple processors at a time

6. The first user
interfaces were not
graphical.
You can still access
DOS by searching
“CMD” in your start
menu.

7. • Main Purpose of the OS
• Convenience
• The OS is responsible for
controlling the computer
hardware, management of
files and control of I/O
devices.
• Efficiency
• The OS becomes responsible
for managing resources
(movement, storage, and
processing of data).
• Adaptability
• OSs should be designed in a
way that allows them to be
tested, developed, and
changed.

8. What the
user sees
The Kernel
controls work
load and
processes.
Shares RAM
memory
among
processors
that need to
use it.
Controls how
files are stored
and accessed by
applications.
The processor
controls the
processing of data.
OS does the
scheduling.

9. • The resources
of a physical
computer are
shared to
create virtual
machines.