Basic Computer Concepts
Data Representation and
Digital Electronics
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Data Representation
v makes it possible to convert letters,
sounds, and images into electrical signals
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Digital Electronics
v makes it possible for a computer to
manipulate simple “on” and “off” signals
to perform complex tasks
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
Why are computers digital ?
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Digital Device
v works with discrete -distinct or separate data or digits, such as 1 and 0
Analog Device
v works with continuous data
Computers are digital because computer
designers have found it to be a relatively
simple, dependable, and adaptable
technology.
A digital computer is a simpler technology
than an analog computer.
Most computers use the simplest type of digital
technology, their circuits have only two
possible states.
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
How can a computer represent numbers using
bits ?
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Computers represent numeric data using the
binary number system, also called “base 2”
Numeric Data
v the numbers that might be used in
arithmetic operations
Binary Number System
v
v
v
has only two (2) digits : 0 and 1
allows computers to represent virtually any
number simply by using 0s and 1s
conveniently translates into electrical “on”
and “off” signals
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
How can a computer represent words and
letters using bits ?
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Character Data
consists of letters, symbols and numerals
that will not be used in arithmetic
calculations
A digital computer uses a series of bits to
represent letters, characters, and numerals.
ASCII
v
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v
v
v
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pronounced as “ ASK ee”
stands for American Standard Code for
Information Interchange
requires only seven bits for each character
Extended ASCII
v
v
v
a superset of ASCII
uses eight bits to represent each
character
provides codes for 128 additional
characters
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
How can a computer represent words and
letters using bits ?
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EBCDIC
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pronounced as “EB seh dick”
v stands for Extended Binary Coded Decimal
Interchange Code
v an alternative 8-bit code usually used by
IBM mainframe computers
UNICODE
v
v
v
pronounced as “YOU ni code”
provides codes for 65,000 characters and
makes use of 16 bits
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
How does a computer convert sounds and
pictures into codes ?
v
v
v
A computer must somehow digitize colors,
notes, and instrument sounds into 1s and
0s, in order to work with sounds and
pictures.
Computers convert colors and sounds into
numbers, which can be represented by
bits.
A red dot on your computer screen might
be represented by 1100, a green dot by
0010.
Computer Hardware
Basic Computer Concepts
Digital Data
Representation
When a computer works with a series of 1s and
0s, how does it know which code to use?
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All of the things that computer works with is
stored in files as a long series of 1s and 0s.
The computer needs to know whether to
interpret those 1s and 0s as ASCII code, binary
numbers, or the code for a picture or sound.
Most computer files contain a file header with
information on the code that was used to
represent the file data, to avoid confusion.
A computer can now tell how a file’s contents
were coded by reading the header information.
Computer Hardware
Basic Computer Concepts
Digital Electronics
How can I tell the difference between bits and
bytes?
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bit
v
v
binary digit
can be further abbreviated as a lowercase
“b”
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byte
v composed of eight (8) bits
v usually abbreviated as an uppercase “B”
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nibble
v composed of four (4) bits
v a halfway between a little bit and a big
byte
Storage space is usually expressed in bytes
while transmission speeds are expressed in
bits.
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Computer Hardware
Basic Computer Concepts
Digital Electronics
How does a computer store and transport all of
those bits ?
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Bits take the form of electrical pulses that can
travel over circuits.
The circuits, chips, and mechanical
components forming a computer are designed
to work with bits.
These components are housed within the
computer’s system unit.
Computer Hardware
Basic Computer Concepts
Digital Electronics
How do chips fit together to make a computer?
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Motherboard
v
v
v
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also known as main board
the computer’s main circuit board
houses all essential chips and provides
connecting circuitry between them
Some chips are permanently soldered in place,
while other chips are plugged into special
sockets and connectors.
The chips might be gathered together on a
separate small circuit board, which can then
be plugged into a special slot-like connector.
Computer Hardware
Basic Computer Concepts
Microprocessor Basics
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Microprocessor
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sometimes known as processor
v an integrated circuit designed to process
instructions
v the most significant component of
computer and usually the most expensive
single component
v executes instructions that are provided by
a computer program
Instruction Set
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list of instructions that a microprocessor
can perform
v hardwired into the processor’s circuitry
comprising of basic arithmetic and logical
operations, fetching data, and clearing
registers
Memory
v
v
v
is the electronic that holds place for
instructions and data which the
microprocessors can reach quickly
Computer Hardware
Basic Computer Concepts
Today’s Microprocessors
Which companies produce most of today’s
popular microprocessors ?
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Intel
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world’s largest chipmaker and supplies a
sizeable percentage of the
microprocessors that power personal
computers
v introduced the world’s first
microprocessor , the 4004, during 1971
AMD (Advanced Micro Devices)
v
v
v
Intel’s chief rival in the PC chip market
produces microprocessors that work just
like Intel's chips, but a lower price
Computer Hardware
Basic Computer Concepts
Today’s Microprocessors
Which of the microprocessors is the best ?
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Intel
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Original Pentium : 1993
v Pentium II : 1997
v Pentium III : 1999
v Pentium IV: 2000
v Itanium : 2001
v Celeron processors : Intel’s budget model
AMD
v
v
v
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Athlon processors : Direct competitors to
Intel’s Pentium line
Duron processor : AMD’s budget model
The microprocessor that’s “best” for you
depends on your budget and the type of work
and play that you plan to do.
Computer Hardware