2. Chapter 3
THE COMPUTER SYSTEM
3. SYSTEM
Is a collection of elements that work together to solve a specific
problem. It can also be defined as a systematic sequence of
operation to produce specific results.
A computer system is combination of six elements namely Hardware,
Software, People ware, Data/Information, Procedures and
Communication. A computer must be a part of a system to be
useful.
4. HARDWARE
Refers to the physical components that perform the function of data
presentation, data input, data manipulation, data storage and
output data.
Hardware is categorized as Input, Output, Processing, Storage and
Communications Hardware.
5. INPUT HARDWARE
Consist of devices that take data and programs that people can read
or comprehend and convert them to a form that computer can
process.
6. TWO TYPES OF INPUT DEVICES
7. Keyboard
A device that converts letters, numbers and other character into
electrical signals that are machine-readable data by the computers
processor. The keyboard is also referred to as the main input
peripheral used by all computers. The keyboard allows the user
input and action with the computer. Much like many type writers,
the keyboard has all the letters of the alphabet, numbers0 - 9 and
additional special operational keys.
8. TYPESOF KEYBOARDS
9. QWERTY Keyboard
Developed by Sholes in 1868 and is now the official standard of
computer keyboards. The layout of the QWERTY keyboard was designed
to help prevent stuck keys. Now with the new technology, stuck keys
are no longer an issue; and with the position of the keys, the
hands are held close together helping to cause Carpal Tunnel
Syndrome. Given all the above problems, this is the most widely
used keyboard because the lack of options, can be used without
training, is used because of the difficulty of having to teach a
different keyboard, and is cheap and is easy to find.
10. DVORAK KEYBOARD
Developed by Dr. August Dvorak in 1936 as solution to the outdated
QWERTY keyboard. The layout of the keys on this keyboard make it
easier and faster to type on when compared to the other
keyboard.
11. CHICLET KEYBOARD
Very small keyboard that was introduced with the PC Jr. with small
keys spread out.
12. DIRECT-ENTRY DEVICE
13. DIRECT-ENTRY DEVICE
Refers to many forms of data entry devices that are not keyboards.
Direct entry devices create machine-readable data on a magnetic
media or paper or feed it directly into the computers
processor.
Pointing Device is any computer hardware component(specifically
human interface device) that allows a user to input
spatial(continuous and multi-dimensional) data to a computer. CAD
systems and graphical user interfaces(GUI) allow the user to
control gesturespoint, click, and drag -typically by moving a
handheld mouse across the surface of the physical desktop and
activating switches on the mouse. Movements of the pointing device
are echoed on the screen by movements of the mouse pointer (or
cursor) and other visual changes.
14. Direct Entry
Pointing Devices
15. MOUSE
A device that is rolled about on a desktop to direct a pointer on
the computers screen or display screen.
16. TRACKBALL
Is a movable, on top of a stationery device, that is rotated with
the fingers or palm of the hand. In the fact, the trackball looks
like a mouse turned up-side down.
17. JOYSTICK
Is a pointing device that consist of a vertical handle like a
gearshift lever on a base with one or two buttons.
18. TOUCH SCREEN
Is a video-display screen that has been sensitized to receive input
from the touch of a finger. The screen is covered with a plastic
layer, behind which are invisible beams of infra-red light.
19. LIGHT PEN
Is a sensitive stylus, or pen-like device connected by a cable to a
computer terminal. Light pens are used by engineers, graphic
designers and illustrators.
20. DIGITIZING TABLET
Consist of a tablet connected by a cable to a stylus. A stylus is a
pen-like device with which the user sketches an image. Digitizing
tablets are used primarily in design and engineering. Pen-based
computer system uses a pen-like stylus to enter handwriting and
marks into a computer.
21. SCANNINGDEVICES
These are device that translate images of text, drawings, photos,
and the like info digital form. Scanning devices include:
22. Imaging Systems
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