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AMADI VERA HOMA
MEDICAL LABORATORY SCIENCE
GST 115: INTRODUCTION TO ICT
100 LEVEL
THE CATEGORIES OF HARDWARE
There are five categories of hardware which include;
a.
b.
c.
d.
e.
f.
Central Processing Unit (CPU)
Main Memory
Secondary Storage
Input Devices
Output Devices
Network Hardware
INPUT DEVICES
All computer hardware components that are instrumental in feeding data to a
computer system are categorized as input devices. An input device is any hardware
device that sends data to a computer, allowing you to interact with and control the
computer. An input device can also be defined as a peripheral (piece of computer
hardware equipment) used to provide data and control signals to an information
processing system such as a computer or information appliance. Examples of input
devices include keyboards, mice, scanners, digital cameras and joysticks.
Examples:
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Audio conversion device
Barcode reader
Biometrics (e.g. fingerprint scanner)
Business Card Reader
Digital camera and Digital Camcorder
Electroencephalography (EEG)
Gamepad, Joystick, Paddle and Steering wheel
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Gesture recognition
Graphics tablet
Keyboard
Light gun and light pen scanner
Mouse
Magnetic-stripe reader
CENTRAL PROCESSING UNIT (CPU):
A central processing unit (CPU) is the electronic circuitry within a computer that
carries out the instructions of a computer program by performing the basic
arithmetic, logical, control and input/output (I/O) operations specified by the
instructions. The CPU is divided into two: The Arithmetic and Logical Unit (ALU)
and the Control Unit (CU). Sometimes referred to simply as the central processor,
but more commonly called processor, the CPU is the brains of the computer where
most calculations take place. In terms of computing power, the CPU is the most
important element of a computer system.
THE ARITHMETIC AND LOGIC UNIT (ALU): This is a digital circuit within
the processor that performs integer arithmetic and bitwise logic operations. The
inputs to the ALU are the data words to be operated on (called operands), status
information from previous operations, and a code from the control unit indicating
which operation to perform. Depending on the instruction being executed, the
operands may come from internal CPU registers or external memory, or they may
be constants generated by the ALU itself.
When all input signals have settled and propagated through the ALU circuitry, the
result of the performed operation appears at the ALU's outputs. The result consists
of both a data word, which may be stored in a register or memory, and status
information that is typically stored in a special, internal CPU register reserved for
this purpose.
The Control Unit of the CPU contains circuitry that uses electrical signals to
direct the entire computer system to carry out stored program instructions. The
control unit does not execute program instructions; rather, it directs other parts of
the system to do so. The control unit communicates with both the ALU and
memory.
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. Examples of output devices
include:
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Speakers
Headphones
Screen (Monitor)
Printer
Voice output communication aid
Automotive navigation system
Projector
Television
Radio
SECONDARY STORAGE DEVICES: Alternatively referred to as external
memory, secondary memory, and auxiliary storage, a secondary storage device is a
non-volatile device that holds data until it is deleted or overwritten.
Secondary storage devices can be divided into three:
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Magnetic Media: Magnetic storage is the storage of data on a magnetized
medium. Magnetic storage uses different patterns of magnetization in a
magnetisable material to store data and is a form of non-volatile memory.
Examples of magnetic storage media include floppy disks, magnetic recording
tape, hard disk and magnetic stripes on credit cards.
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Optical Media: Optical media - such as the compact disk (CD) - are storage
media that hold content in digital form and that are written and read by a laser;
these media include all the various CD and DVD variations, as well as optical
jukeboxes and auto changers. Optical media have a number of advantages over
magnetic media such as the floppy disk. Optical disk capacity ranges up to 6
gigabytes; that's 6 billion bytes compared to the 1.44 megabytes (MB) 1,440,000 bytes - of the floppy. One optical disk holds about the equivalent of
500 floppies worth of data. Durability is another feature of optical media; they
last up to seven times as long as traditional storage media. Examples include the
CD and the DVD.
Semiconducting Media: They are also known as flash memory. They use
semi-conductor clips to store data. They are very reliable and durable. They are
silent in operation and they are used in portable devices such as digital cameras,
PDA and MP3. Examples are Compact flash card and Secure Digital Card.
MAIN MEMORY: Main memory is where programs and data are kept when the
processor is actively using them. When programs and data become active, they are
copied from secondary memory into main memory where the processor can
interact with them. A copy remains in secondary memory.
Main memory is intimately connected to the processor, so moving instructions and
data into and out of the processor is very fast. Main memory is where programs
and data are kept when the processor is actively using them. When programs and
data become active, they are copied from secondary memory into main memory
where the processor can interact with them. A copy remains in secondary memory.
Main memory can be divided into three;
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Random Access Memory (RAM): Random-access memory is a form of
computer data storage. A random-access memory device allows data items to be
accessed (read or written) in almost the same amount of time irrespective of the
physical location of data inside the memory. In contrast, with other directaccess data storage media such as hard disks, CD-RWs, DVD-RWs and the
older drum memory, the time required to read and write data items varies
significantly depending on their physical locations on the recording medium,
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due to mechanical limitations such as media rotation speeds and arm movement
delays.
Read Only Memory (ROM): Read-only memory is a class of storage medium
used in computers and other electronic devices. Data stored in ROM can only
be modified slowly, with difficulty, or not at all, so it is mainly used to
distribute firmware (software that is very closely tied to specific hardware, and
unlikely to need frequent updates).
Complementary metal–oxide–semiconductor (CMOS): This is a technology
for constructing integrated circuits. CMOS technology is used in
microprocessors, microcontrollers, static RAM, and other digital logic circuits.
CMOS technology is also used for several analog circuits such as image sensors
(CMOS sensor), data converters, and highly integrated transceivers for many
types of communication. Complementary metal-oxide semiconductor, or
CMOS, typically refers to a battery-powered memory chip in your computer
that stores startup information. Your computer's basic input/output system
(BIOS) uses this information when starting your computer.
NETWORK HARDWARE: Networking hardware may also be known as
network equipment or computer networking devices. Network hardware is the
individual components of a network system that are responsible for transmitting
data and facilitating the operations of a computer network. Although a network
contains many hardware components, there are several basic categories that make
up the complete operations of a network system. Examples include; routers,
bridges, network interface card, gateways, hubs, modem and so on.