Transcript Intro to Computer Systems - City Tech OpenLab

EMT1111
Logic and Problem Solving
Lecture 2
Dr. José M. Reyes Álamo
Outline
• What is computation?
• What is a computer?
• Hardware
• Software
• Bits and Bytes
• Data (storing and transmitting)
• Programming Languages
• Computer Networks
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What is Computation?
• Computation is the manipulation of data by
either humans or machines
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What is a computer?
• A computer is a device capable of performing
arithmetic and logical operations at speeds much
faster than human.
• A computer is able to:
– Accept input
– Do computation (manipulate data executing
logical and arithmetic operations)
– Output data
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People!
Computers used to refer to people
In WWII, computers were people who did difficult
calculations by hand, for things like ballistic tables.
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Modern Computers
Computer categories
• A microcomputer is a computer that can perform all of its input,
process, output, and storage activities by itself.
• A minicomputer is often used in situations where a
microcomputer is not powerful enough but a mainframe is too
expensive.
• A mainframe is a large, expensive, but powerful computer that
can handle hundreds or thousands of input/output operations.
• A supercomputer is the fastest, most powerful, and most
expensive computer used for applications that require complex
and sophisticated mathematical calculations.
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Other classifications of computer systems
•Personal computer
•Stand-alone computer
•Server
•Client computer
•Network computer
•Workstation
•Terminal
•Embedded System
It’s All About the Switch
•The basic component of most digital circuitry is
a simple switch.
•A switch’s function, “switches” values:
–On or Off
–True or False
–1 or 0
Electronic Switch
• Early computers used vacuum tubes as switches
• Later, transistors were used as substitutes
Switches for Boolean Circuits
• Switches can be used to construct more complicated
functions, such as Boolean circuits (AND on left, OR
on right)
Manipulations of the underlying data (binary code) is
done by using electronic gates.
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A Very Interesting Switch
Transistors have three features that make them the
fundamental element of the computer revolution:
• Size
• Quantity
• Speed
Size
Originally very large
Shockley transistor
Kilby integrated circuit
Intel’s first CPU
By 1971, Intel had created a “computer on a chip,” the
4004 microprocessor, the size of a fingernail with 2300
transistors.
Silicon transistor timeline
You will learn more on about this in future courses
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Moore’s Law
• Gordon Moore is one of the founders of the chip
maker Intel
• In 1965, he observed the growth rate of the number
of transistors in a circuit
• Made a famous prediction that the number of
transistors on a chip doubles every 18 months for the
same cost
– He observed that roughly, this has been the case since 1965
Parts of a computer
Computer organization and
architecture
Main Components
• Hardware
– Physical Devices: processor, memory, keyboard, monitor,
mouse, etc.
• Software
– Executable Programs: word processor, spread sheet,
internet browser, etc.
• Users
– People, other hardware and software.
Hardware
secondary storage
processor
primary
storage
input device
output device
network
Processor
• The processor is the “brain” of a computer.
• The processor controls the other devices and
performs calculations
Primary Storage
• Stores instructions and data for current programs
• Other names: primary memory, main memory, RAM
(Random Access Memory)
• Memory is “dynamic” as it requires power to retain
information
Peripheral Devices
• Secondary storage devices
– Disk (hard & floppy), tape, USB drives, flash drives, etc.
• Input devices
– Keyboard, mouse, camera, microphone, etc.
• Output devices
– Monitor, printer, speaker, etc.
• Network
– Wireless, Bluetooth, Ethernet, etc.
Secondary Storage
• Nonvolatile -- information is recorded magnetically so
power is not needed
• Disks hold Gigabytes (billions of bytes)
• Cheaper, but slower than primary storage
• Not accessed directly by the CPU
Software
• The programs available for execution
• Classification
– System software
– Application software
System Software
• Operating system (OS)
– Manages system resources
– Provides an interface to the user: interface with operating
system
– Popular Oss: Windows, Mac OS, Linux, Unix
Application Software
• Programs that perform specific tasks for the user (and
use the operating system to interact with the
hardware)
• Examples: word processor, spreadsheet, internet
browser.
What is a Program?
• A sequence of instructions written in machine
language that tells the CPU to take certain actions in a
specific order
• In this course you will learn to create programs
Program Storage
• Machine language instructions are encoded as bit
patterns
• Memory can only hold binary info
• A bit is represented by two-states (e.g. L-R
magnetism, high-low voltage)
• It takes many bits to represent reasonable amounts
of information
Programming Languages
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Programming languages
• Eventually, every program must be translated
into a machine language (1’s and 0’s) that the
computer can understand.
• This translation is performed by compilers,
interpreters, and assemblers.
• When you buy software, you normally buy an
executable version of a program.
– This means that the program is already in machine
language.
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Binary Numbers
• The “switch” nature of transistors make storing
numbers in binary a natural fit.
• Binary uses base 2, as opposed to the decimal
numbering system that uses base 10
Example
• Decimal uses digits 0-9 and positions in a number as
powers of 10
– 73510 = 7*102 + 3*101 + 5*100
• Binary users digits 0,1 and positions in a number as
powers of 2
– 1012 = 1*22 + 0*21 + 1*20
• We can covert from binary to decimal and vice versa
Representing data
 A bit = one binary representation
 A Byte = 8 bits
 Word = 32 bits
 1KB (Kilobyte)= 210 bytes = 1024 bytes
 1MB (Megabyte)= 220 bytes = 1,048,576 bytes
 1GB (Gigabyte)= 230 bytes=1,073,741,824 bytes
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Words
• A word of storage is the basic unit used by a
computer.
• A typical computer today is a 32 bit computer,
meaning its word size is 32 bits
– Today we also have 64-bit machines
• The word size imposes a limit on the memory and the
data that can be stored
Word sizes have changed
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Physical states representing bits
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Representing Data in Binary
• Letters and symbols are encoded as binary numbers
• Both ASCII and Unicode are encodings for particular
letters and symbols
• ASCII (American Standard Code for Information
Interchange) is used for encoding the English
alphabet (http://asciiset.com/ )
• Unicode is used to encode more characters such as
those used in Arabic and Asian languages (Unicode)
Images
• Digital images consist of individual colors in a matrix.
• Each individual color is called a pixel.
• The color of a pixel is encoded using numbers as well.
Bits <-> information
 Representing images:
– An image is made up of thousands of very small dots
– These dots are called pixels.
– The color of each pixel can be represented as combination
of three colors, Red, Blue, and Green
– Each primary color component (R,G,B) can be represented
as an 8-bit byte. An 8-bit string can represent 28 = 256
different things.
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Bits <-> information
 Representing images:
– In this case, the 8-bit string for Red represents different
amounts of Red, from 0 (none) to 255 (lots). The same for
Green and Blue.
– If there are 256 different quantities of R, G, and B, then we
can mix these together in 256 × 256 × 256 = 16,777,216
ways. It is believed that the human eye can distinguish
about 10 million different colors.
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Bits <-> information
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Networking
What is a computer network?
A computer network is established when a
group of computers is connected to each
other for communication. The purpose of
this connection or network is to share the
resources within the connected units.
You will learn more about networks in EMT2455 & CET4773
The Internet
is a network of networks!
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Computer networks are useful
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Homework
 Go to:
http://openlab.citytech.cuny.edu/emt1111s13/a
ssignments
 Complete Lab and Reading Assignments for
Week 2
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