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Technology Guide 1
Hardware
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What is a Computer System
 Computer hardware is composed of the following
components:
Central processing unit (CPU)
Input devices
Output devices
Primary storage
Secondary storage
Communication devices
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Computer System
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Representing Data
 Today’s computers are based on integrated circuits (chips), each
of which include millions of subminiature transistors.
 The “on-off” states of the transistors are used to establish a
binary 1 or 0 for storing one binary digit, or bit.
 A byte is a sufficient number of bits to represent specific
characters— usually 8 bits.
 The two most commonly used coding schemes are:
1. ASCII (American National Standard Code for Information
Interchange)
2. EBCDIC (Extended Binary Coded Decimal Interchange Code)
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Representing Pictures
 Pictures are represented by
a grid overlay of the picture.
 The computer measures the
color (or light level) of each
cell of the grid. The unit
measurement of this is
called a pixel.
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Representing Time
 Time is represented in fractions of a second. The following
are common measures of time:
 Millisecond 1/1000 seconds
 Microsecond 1/1,000,000 seconds
 Size is measured by the number of bytes. Common
measures of size are:
 Kilobyte 1,000 bytes (actually 1024)
 Megabyte 1,000 kilobytes 106 bytes
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Evolution of Computers
 The first generation of computers, 1946–1956
 Used vacuum tubes to store process information
 The second generation of computers, 1957–1963
 Used transistors for storage and processing information
 Third-generation of computers, 1964–1979
 Used integrated circuits for storing and processing information
 Early to middle fourth-generation computers, 1980–1995
 Used very large-scale integrated (VLSI) circuits to store/ process
information
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Evolution of Computers (cont.)
 Late fourth-generation computers, 1996–present
 Use grand-scale integrated (GSI) circuits to store/ process
information
 Fifth Generation of Computers, Present
 Uses massively parallel processing to process multiple instructions
simultaneously
 Future Generations of computers
 DNA Computers
 Optical Computers
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Types of Computers
 Supercomputers
 The computers with the most processing power
 Use the technology of parallel processing
 Massively parallel computers
 Uses a large number of processors
 The processors divide up and independently work on small chunks
of a large problem
 Mainframes
 Not as powerful and generally not as expensive as supercomputers
 Most often used by large corporations
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Types of Computers (cont.)
 Minicomputers (midrange computers)
 Smaller and less expensive than mainframe computers
 Designed to accomplish specific tasks
 Workstations
 Based on RISC (reduced instruction set computing) architecture
 Provide high-speed calculations and high-resolution graphic displays
 Microcomputers (micros or personal computers, PCs)
 The smallest and least expensive category of general-purpose computers
 Four classifications based on their size:
– Desktops
- Note books
– Laptops
- Palmtops
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Types of Computers (cont.)
 Personal digital assistant (PDA)
 A palmtop computer that combines a fast processor with a multitasking
operating system
 Smart Card
 An even smaller form of computer that has resulted from the continuing
shrinkage of integrated circuits
 Uses for smart cards are appearing rapidly and include;
– Checkbooks
– a bank ATM that can “deposit money” into the card’s memory for
“withdrawal” at retail stores
– transporting data between computers
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Network Computers & Terminals
 Network computer (NC)
 “thin” computer
 desktop terminal that does not
store software programs or
data permanently
 Windows-based terminals
(WBTs)
 subset of the Network
computer
 reduces maintenance &
support costs
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Central Processing Unit
 The central processing unit (CPU) is also referred to as a
microprocessor because of its small size.
 The CPU is the center of all computer-processing activities,
where all processing is controlled, data are manipulated,
arithmetic computations are performed, and logical comparisons
are made.
 The CPU consists of the;
1. Control unit
2. Arithmetic-logic unit (ALU)
3. Primary storage (or main memory)
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Primary Storage
Primary storage, or main memory, stores data and program
statements for the CPU. It has four basic purposes.
1. To store data that have been
input until they are transferred to
the ALU for processing.
3. To hold data after processing until
they are transferred to an output
device.
2. To store data that have been
input until they are transferred to
the ALU for processing.
4. To hold program statements or
instructions received from input
devices and from secondary
storage.
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Buses
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A bus is a channel (or shared data path) through which data is
passed in electronic form.
Three types of buses link the CPU, primary storage, and the
other devices in the computer system.
1. The data bus moves data to and from primary storage.
2. The address bus transmits signals for locating a given
address in primary storage.
3. The control bus transmits signals specifying whether to “read”
or “write” data to or from a given primary storage address,
input device, or output device.
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Control Unit
 The control unit reads
instructions and directs the
other components of the
computer system to perform
the functions required by the
program.
 The control unit does not
actually change or create
data; it merely directs the
data flow within the CPU.
 The Machine cycle is the
series of operations required
to process a single machine
instruction.
 Each machine cycle consists
of the;
 instruction cycle, and the
 execution cycle
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Memory
 There are two categories of memory:
1. The register
 This is part of the CPU and is very fast.
 It allows for the fast storage and retrieval of data and
instructions during the processing.
2. Internal memory chips
 These reside outside the CPU and are slower.
 The internal memory is used to store data just before they are
processed by the CPU.
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Random-Access Memory
 Random-access memory (RAM) is the place in which
the CPU stores the instructions and data it is processing.
 The advantage of RAM is that it is very fast in storing and retrieving
any type of data.
 Dynamic random access memories (DRAMs) are the
most widely used RAM chips.
 Synchronous DRAM (SDRAM) is a relatively new and
different kind of RAM.
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Read-Only Memory
 Read-only memory (ROM) is that portion of primary
storage that cannot be changed or erased.
 Programmable read-only memory (PROM) is a
memory chip on which a program can be stored.
 Erasable programmable read-only memory (EPROM)
is a special type of PROM that can be erased by
exposing it to ultraviolet light.
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Microprocessor Speed
The speed of a chip depends on four things:
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Clock speed
Word length
Data bus width
Design of the chip
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Parallel Processing
 A Parallel Processing System is a computer system with two or
more processors.
 Today, some PCs have 2 to 4 processors while workstations have
20 or more.
 Processing data in parallel speeds up processing.
 Massively parallel processor (MPP) systems are systems with
large numbers of processors.
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Microprocessor Evolution
 Microprocessors have become dramatically faster, more
complex, with increasing numbers of transistors embedded in the
silicon wafer.
 Chips are now being manufactured from gallium arsenide
(GaAs), a semiconductor material inherently much faster than
silicon.
 Intel has incorporated MMX (multimedia extension) technology in
its Pentium microprocessors.
 MMX improves video compression/decompression, image manipulation,
encryption, and input/output processing.
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Microprocessor Architecture
 Computer architecture refers to the arrangement of the components
and their interactions. It includes;





the instruction set
the number of the processors
the structure of the internal buses
the use of caches
the types and arrangements of input/output (I/O) device interfaces.
 An instruction set is the set of machine instructions that a processor
recognizes and can execute.
 Today, there are two main instruction set strategies:
– Complex instruction set computer (CISC)
– Reduced instruction set computer (RISC)
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Input/ Output Devices
 The input/output (I/O)
devices of a computer are
not part of the CPU, but are
channels for communicating
between the external
environment and the CPU.
 Input devices deliver data
and instructions into the
computer.
 Output devices provide
processing results.
 I/O devices are subclassified
into the following categories;
 Secondary storage devices:
primarily disk and tape
drives
 Peripheral devices: any
input/output device that is
attached to the computer
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Secondary Storage
 Secondary Storage is separate from primary storage and the
CPU, but directly connected to it. It provides the computer with
vastly increased space for storing and processing large
quantities of software and data.
 Secondary storage media include;
 Magnetic tape
 Magnetic disk
 Magnetic diskette
 Optical storage
 Digital videodisk (DVD)
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Input Devices
Users can command the computer and communicate with it by
using one or more of the following input devices.
 Keyboard. The most common input device is the keyboard. The
keyboard is designed like a typewriter but with many additional
special keys.
 Mouse. The computer mouse is a hand-held device used to
point a cursor at a desired place on the screen.
 Touch Screen. The user activates an object on the screen by
touching it with his or her finger.
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Input Devices (cont.)
 Touchpad. A touchpad or trackpad is a small, flat, rectangular
pointing device that is sensitive to pressure and motion.
 Light Pen. A light pen is a special device with a light-sensing
mechanism, which is used to touch the screen.
 Joystick. Joysticks are used primarily at workstations that can
display dynamic graphics. They are also used in playing video
games. The joystick moves and positions the cursor at the
desired object on the screen.
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Input Devices (cont.)
 Automated Teller Machines (ATMs). ATMs are interactive
input/output devices that enable people to obtain cash, make
deposits, transfer funds, and update their bank accounts instantly
from many locations.
 Electronic Form. In form interaction, the user enters data or
commands into predesignated spaces (fields) in a form. The
headings of the electronic form serve as a prompt for the input.
 Whiteboard. A whiteboard is an area on a display screen that
multiple users can write or draw on.
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Source Data Automation
 Source data automation captures data in computer-readable
form at the moment the data are created.
 Examples of Source Data Automation:
 Point-of-sale systems
 Optical bar-codes
 Code scanners
 Handwriting recognizers
 Voice recognizers
 Magnetic ink character readers (MICR)
 Digitizers
 Digital Cameras
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Output Devices
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Output Devices (cont.)
The output generated by a computer can be transmitted
to the user via several devices and media.
 Monitors
 Impact Printers
 Nonimpact Printers
 Plotters
 Voice Output
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Communications Media
Computer
Motion image
 CRT and terminals
 CD-ROM
 Computer interactive
videodisc
 Digital video interactive
 Compact disc interactive
 Computer simulation
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Videodisc (cassette)
Motion pictures
Broadcast television
Teleconference/videoconfe
rence
 Animation & Virtual Reality
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Communications Media (cont.)
Audio
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Tape/cassette/record
Teleconference
Audioconference
Sound digitizing
Microphone
Compact disc
Music
Projected still visuals
 Slide & Overhead
Graphic materials
 Pictures
 Printed job aids
 Visual Displays
Text
 Printouts
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