A/L ICT Topic: 02 Section: 01
Computer
A computer is
an electronic device, operating under the control of instructions stored in its
own memory that can accept data (input), process the data according to
specified rules, produce information (output), and store the information for
future use.
Functionalities of a computer
Any digital
computer carries out five functions in gross terms:
Computer
Components
Any kind of
computers consists of HARDWARE AND SOFTWARE.
Hardware:
Computer
hardware is the collection of physical elements that constitutes a computer
system. Computer hardware refers to the physical parts or components of a
computer such as the monitor, mouse, keyboard, computer data storage, hard
drive disk (HDD), system unit (graphic cards, sound cards, memory,
motherboard and chips), etc. all of which are physical objects that can be
touched.
Input device is
any peripheral (piece of computer hardware equipment to provide data and
control signals to an information processing system such as a computer or other
information appliance.
Input device
Translate data from form that humans understand to one that the computer
can work with. Most common are keyboard and mouse
Input device
Translate data from form that humans understand to one that the computer
can work with. Most common are keyboard and mouse
Example of Input Devices:-
1.
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Keyboard
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2.
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Mouse
(pointing device)
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3.
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Microphone
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4.
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Touch screen
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5.
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Scanner
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6.
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Webcam
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7.
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Touchpads
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8.
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MIDI keyboard
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9.
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Joystick
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10. Graphics
Tablets
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11. Cameras
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12. Pen Input
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13. Video
Capture Hardware
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14.
Microphone
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15.
Trackballs
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16. Barcode
reader
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17. Digital
camera
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18. Gamepad
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19.
Electronic Whiteboard
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Note: The most common use keyboard is the QWERTY
keyboard. Generally standard Keyboard has 104 keys.
Central Processing Unit (CPU)
A CPU is brain
of a computer. It is responsible for all functions and processes. Regarding
computing power, the CPU is the most important element of a computer system.
The CPU is comprised of three main parts:
*
Arithmetic
Logic Unit (ALU): Executes all arithmetic and logical
operations. Arithmetic calculations like as addition,
subtraction, multiplication and division. Logical operation like compare
numbers, letters, or special characters
* Control Unit
(CU): controls and
co-ordinates computer components.
1.
Read the code for the next instruction to be
executed.
2.
Increment the program counter so it points to
the next instruction.
3.
Read whatever data the instruction requires
from cells in memory.
4.
Provide the necessary data to an ALU or
register.
5.
If the instruction requires an ALU or
specialized hardware to complete, instruct the hardware to perform the
requested operation.
*
Registers: Stores the data that is to be executed next,
"very fast storage area".
Primary Memory:-
1.
RAM: Random Access Memory (RAM) is a memory scheme
within the computer system responsible for storing data on a temporary
basis, so that it can be promptly accessed by the processor as and when needed.
It is volatile in nature, which means that data will be erased once supply to
the storage device is turned off. RAM stores data randomly and the processor
accesses these data randomly from the RAM storage. RAM is considered
"random access" because you can access any memory cell directly if
you know the row and column that intersect at that cell.
2.
ROM (Read Only Memory): ROM is a permanent form of
storage. ROM stays active regardless of whether power supply to it is
turned on or off. ROM devices do not allow data stored on them to be modified.
Secondary Memory:-
Stores data and
programs permanently: it’s retained after the power is turned off
1.
Hard drive (HD): A hard disk is
part of a unit, often called a "disk drive," "hard drive,"
or "hard disk drive," that store and provides relatively quick access
to large amounts of data on an electromagnetically charged surface or set of surfaces.
2.
Optical Disk: an optical disc drive (ODD) is a disk drive
that uses laser light as part of the process of reading or writing data to or
from optical discs. Some drives can only read from discs, but recent drives are
commonly both readers and recorders, also called burners or writers. Compact
discs, DVDs, and Blu-ray discs are common types of optical media which can be
read and recorded by such drives. Optical drive is the generic name; drives are
usually described as "CD" "DVD", or "Bluray",
followed by "drive", "writer", etc. There are three main
types of optical media: CD, DVD, and Blu-ray disc. CDs can store up to 700
megabytes (MB) of data and DVDs can store up to 8.4 GB of data. Blu-ray discs,
which are the newest type of optical media, can store up to 50 GB of data. This
storage capacity is a clear advantage over the floppy disk storage media (a
magnetic media), which only has a capacity of 1.44 MB.
3.
Flash Disk
4.
A storage module made of flash memory chips. A
Flash disks have no mechanical platters or access arms, but the term
"disk" is used because the data are accessed as if they were on a
hard drive.
The disk storage structure is emulated.
Output devices
An output
device is any piece of computer hardware equipment used to communicate the
results of data processing carried out by an information processing system
(such as a computer) which converts the electronically generated information
into human-readable form.
1.
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Monitor
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2.
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LCD
Projection Panels
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3.
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Printers (all
types)
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4.
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Computer
Output Microfilm (COM)
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5.
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Plotters
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6.
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Speaker(s)
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7.
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Projector
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Note Basic types of monitors are:
A) Cathode Ray Tube (CRT).
B) Liquid Crystal Displays (LCD).
C) Light-emitting diode (LED).
Printer types: 1-Laser
Printer. 2-Ink Jet Printer. 3-Dot Matrix Printer
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