The document discusses the basic components of a computer system including hardware and software. It describes the main hardware components as the motherboard, central processing unit (CPU), memory (RAM and hard disk drive), input devices like the keyboard and mouse, and output devices like monitors. It provides details on the functions of the CPU, RAM, hard disk drives, and differences between hard disk drives and solid state drives. It also explains common keyboard shortcuts and mouse functions like left clicking, right clicking, and double clicking.

1. Computer Essential
 FIRST STAGE
 Public Health
 College of health and medical technology, shekhan
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2. Computer: Definition
A computer is a machine that can be programmed to manipulate symbols. Its
principal characteristics are:
 It responds to a specific set of instructions in a well-defined manner.
 It can execute a prerecorded list of instructions (a program).
 It can quickly store and retrieve large amounts of data.
The actual machinery (wires, transistors, and circuits) is called hardware.
the instructions and data are called software.
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Hardware and Software
A computer system is made up of a combination of hardware and software.

3. Hardware:
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All of the electronic and mechanical equipment in a computer is called the
hardware. include:
 Motherboard
 Hard disk
 RAM
 Power supply
 Processor
 Case
 Monitor
 Keyboard
 Mouse
 Mouse
 Speaker
 Headphone
 Microphone
 Printer
 Scanner
 Etc…

4. Software:
The term software is used to describe computer programs that perform a task
or tasks on a computer system.
Software can be grouped as follows:
 System software
1. The Operating System
2. Utility programs
 Device drivers
 Application Software
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5. Software:
 System software:
1. The Operating System:
 Starts the computer
 Provides a user interface
 Manages the computer memory
 Manages storage
 Manages security
 Provides networking and internet facilities
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6. Software:
2. Utility programs
 File management programs
 Uninstall programs
 Disk scanners and defragmenters
 Backup utilities
 Antivirus
 Device drivers
Are programs that control particular hardware devices. They are supplied with
new hardware and must be run so they the hardware can communicate with
the OS. They are supplied with printers, graphics cards, scanners etc.
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7. Software:
 Application Software
 Business software
 Engineering software
 Medical software
 Games
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8. All general-purpose computers require the following hardware components:
 The Motherboard.
 Central processing unit (CPU).
 Memory.
 Mass storage device.
 Input device.
 Output device:
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In addition to these components, many others make it possible for the basic
components to work together efficiently. For example, every computer
requires a bus that transmits data from one part of the computer to another.

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10. 1. The Motherboard
Often called the mainboard or system board, it is the main circuit board for
the computer system. Every device in the computer system will either be part
of the motherboard or connected to it.
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11. 1. The Motherboard
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12. 2. The Processor (CPU)
 The heart of the computer, this is the component that actually executes
instructions organized in programs ("software") which tell the computer
what to do.
The processor’s function is to control the activities of the computer system.
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13. 2. The Processor (CPU)
The central processing unit (CPU) consists of six main components:
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 control unit (CU)
 arithmetic logic unit (ALU)
 registers
All components work together to allow processing and system control.
 cache
 buses
 clock

14. 2. The Processor (CPU)
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15. 3. Memory ( Random Access Memory (RAM))
 Fast, expensive, short-term memory enables a computer to store, at least
temporarily, data, programs, and intermediate results.
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16. 3. Memory ( Random Access Memory (RAM))
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17. 4. Memory :(Hard disk drive)
 Slower, cheaper, long-term memory allows a computer to permanently
retain large amounts of data and programs between jobs.
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18. 4. Memory :(Hard disk drive)
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HDD SSD
Stands for Hard Disk Drive Solid State Drive
Speed
HDD is slower. HDD has higher
latency, longer read/write
times, and supports fewer IOPs
(input output operations per
second) compared to SSD.
SSD is faster. SSD has lower
latency, faster read/writes,
and supports more IOPs (input
output operations per
second) compared to HDD.
Heat, Electricity,
Noise
Hard disk drives use more
electricity to rotate the
platters, generating heat and
noise.
Since no such rotation is
needed in solid state drives,
they use less power and do
not generate heat or noise.
Defragmentation
The performance of HDD
drives worsens due to
fragmentation; therefore, they
need to be periodically
defragmented.
SSD drive performance is not
impacted by fragmentation.
So defragmentation is not
necessary.

19. 4. Memory :(Hard disk drive)
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HDD SSD
Components
HDD contains moving parts - a
motor-driven spindle that holds
one or more flat circular disks
(called platters) coated with a
thin layer of magnetic material.
Read-and-write heads are
positioned on top of the disks;
all this is encased in a metal cas
SSD has no moving parts; it is
essentially a memory chip. It
is interconnected, integrated
circuits (ICs) with an
interface connector. There
are three basic components
- controller, cache and
capacitor.
Weight
HDDs are heavier than SSD
drives.
SSD drives are lighter than
HDD drives because they do
not have the rotating disks,
spindle and motor.
Dealing with
vibration
The moving parts of HDDs make
them susceptible to crashes
and damage due to vibration.
SSD drives can withstand
vibration up to 2000Hz, which
is much more than HDD.

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21. 5. INPUT DEVICES
Input devices accept data and instructions from the user. Following are the
examples of various input devices, which are connected to the computer for
this purpose.
 Keyboard
 Mouse
 Light Pen
 Optical/magnetic Scanner
 Touch Screen
 Microphone for voice as input
 Etc..
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22. 5. INPUT DEVICES
 Keyboard
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23. 5. INPUT DEVICES
 Keyboard shortcuts
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24. 5. INPUT DEVICES
 Keyboard
 Home: Skip to the beginning of the current line.
 End: Skip to the end of the current line.
 Delete: Send a selected file to the Recycle Bin.
 Enter: Open a selected application or file.
 Windows key: Open the Start menu.
 Number lock : The Num Lock key enables and disables the numeric pad.
 Arrow keys : Move the text cursor on the screen to insert or remove text.
referred to as cursor keys, direction keys. It is made up of four keys: the left
arrow (back arrow), up arrow, down arrow, and the right arrow (forward
arrow).
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25. 5. INPUT DEVICES
 Mouse
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26. 5. INPUT DEVICES
 Mouse
 Left click
 Single-click: This is the most common type of mouse click. To single-click,
press the left mouse button once and immediately release it. Single-clicks
are used in a variety of situations
 Double-click: To double-click, click twice in rapid succession. If you do not
click fast enough, however, the computer will register it as a single-click
twice; if you are having trouble, try tapping your finger on the mouse
button instead of pressing it. Use double-clicks for operations
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27. 5. INPUT DEVICES
 Mouse
 Right-click:
 When using the right mouse button, you need only single-click. You will not
cause any problems if you double-click or click twice, but your computer
will not interpret these types of clicking as being any different from a single-
click.
 Right-clicking will cause a drop-down menu to appear with multiple
options. This is called a contextual menu, and the options in the menu will
be different depending on the application you are using and where your
mouse pointer is positioned on the screen when you click.
 From the contextual menu, you can do such things as rename the file or
folder you right-clicked, save it to a different location, or move it to the
Recycle Bin.
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28. 6. OUTPUT DEVICES
Output devices return processed data that is information, back to the user.
Some of the commonly used output devices are:
 Monitor (Visual Display Unit)
 Printers
 Plotter
 Speakers
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