1. Introduction to Computers
Lecture 1
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Web Page and Book List
Main Course Web Page is at:
Recommended Text
Shelly Cashman: Discovering Computer 2011
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Data vs. Information
Data: Representation of a fact or idea
Information: Organized, meaningful data
Data is a representation of a fact or idea. Data can be a number, a word, a picture, or even a recording of sound. For example, the number and the names Derek and Washington are pieces of data.
Information is data that has been organized or presented in a meaningful fashion. When your computer provides you with a contact listing that indicates Derek Washington can be reached by phone at (612) , the data mentioned earlier suddenly becomes useful— that is, it is information.
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Data, Information
Data vs. Information
Data (PLURAL) - SINGULAR IS DATUM
A “given” or fact: a number, a statement, or a picture
The raw facts in the production of information
Information
Data that have meaning within a context
Raw data or data that have been manipulated
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5. Computers Are Data Processing Devices
Computer’s four major functions:
Gathers data (users input data)
Processes data into information
Outputs data or information
Stores data and information
Strictly defined, a computer is a data processing device that performs four major functions:
1. It gathers data (or allows users to input data).
2. It processes that data into information.
3. It outputs data or information.
4. It stores data and information.
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What Computers Do
Basic Components of a Computer
Input devices
Keyboards and pointing devices (mouse)
Output devices
Display or video monitor
Printer
Speakers
Central Processing Unit (CPU)
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What Computers Do
Basic Components of a Computer
Memory and storage devices
Primary storage: RAM (Random Access Memory)
Secondary storage: Storage devices that serve as long-term repositories for data:
Hard disk drives
Recordable CD and DVD drives
Tape drives
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8. Components of a Computer System
Input
Output
Central Processing Unit (CPU)
Memory
Control Unit
Arithmetic Logic Unit
Registers
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9. Bits and Bytes: The Language of Computers
Binary digit
0 or 1
Byte
Eight bits
Each letter, number, and character = a string of eight 0s and 1s
In order to process data into information, computers need to work in a language they understand. This language, called binary language, consists of just two digits: 0 and 1.
Everything a computer does is broken down into a series of 0s and 1s. Each 0 and 1 is a binary digit, or bit for short.
Eight binary digits (or bits) combine to create 1 byte.
In computers, each letter of the alphabet, each number, and each special character (such as sign) consists of a unique combination of 8 bits, or a string of eight 0s and 1s.
As it turns out, if 8 bits are put together there are 256 possible combinations that they can be in. That number of combinations allows for a code that can include all the uppercase and lowercase letters of the alphabet, all 10 digits, punctuation marks, and many other much-used symbols. We call these 8 bits working together a byte. Bytes are the basic measurement for storage in a computer.
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A Bit About Bits
Bits, Bytes, and Buzzwords
Bit-related terminology
Byte
Kilobyte (KB)
Megabytes (MB)
Gigabytes (GB)
Terabytes (TB)
= 8 bits
= 1 Thousand Bytes
= 1 Million Bytes
= 1 Billion Bytes
= 1 Trillion Bytes
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11. Chapter 2 Summary Questions
What devices do you use to get data into the computer?
What devices do you use to get data into the computer?
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12. Chapter 2 Summary Questions
What devices do you use to get information out of the computer?
What devices do you use to get information out of the computer?
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13. Chapter 2 Summary Questions
What’s on the front of your system unit?
What’s on the front of your system unit?
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14. Chapter 2 Summary Questions
What’s on the back of your system unit?
What’s on the back of your system unit?
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History of Computers
Mechanical and electromechanical devices preceded the electronic computer.
Charles Babbage (1830’s): the analytical engine, and Augusta Ada Byron, the first programmer.
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16. Charles Babbage’s Analytical Engine
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17. Electro-Mechanical Devices
(1890’s): electrical tabulating machine, and foundation of IBM (1924).
Aiken’s Mark 1. (1944) based on Babbage’s original design - built at IBM labs, electro-mechanical, weighed 5 tons.
Admiral Grace Hopper worked as programmer on this computer, and coined in the term 'bug' for a computer fault.
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Electronic Computers
To increase speed and reliability, the mechanical components of these early devices were replaced by electronic equivalents.
These fully electronic devices became known as the of computers.
Successive generations of electronic computers have greater speed, smaller size, larger memory.
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First Generation
1st Generation: ( ).
Vacuum Tubes used as switching and storage components.
Atanasoff & Berry (1939) first electronic digital computer.
Turing (1943) Colossus machine built to decode encrypted messages. (*Turing Test)
ENIAC (1946) first general purpose computer. (decimal not binary machine)
UNIVAC (1951) first commercial computer - commissioned for 1950 US census.
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First Generation
Problems with vacuum tube machines:
severe overheating,
manual setting of each instruction,
use of machine language only.
Magnetic core used for memory, punched cards and later magnetic tape for secondary storage.
Computers used for scientific and government purposes.
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First Generation
In 1945 John von Neumann proposed the ‘stored program concept’, with memory to store both data and instructions.
Loading a new program into memory then allows a new function for the computer.
In Von Neumann’s basic design, the program is executed in a sequential manner.
While still the model for most conventional computers, parallel processing has recently challenged this aspect of the traditional computing device
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Second Generation
2nd Generation: ( ). Transistors.
Transistors replaced vacuum tubes. smaller, faster, more reliable, and use less energy
Development of symbolic languages Simpler programming - eg ADD instead of , high level languages Fortran and Cobol.
Provision of system software (OS).
Computers used by military, government and big business.
Problems: 100s or 1000s of transistors required for powerful machines, expensive and cumbersome
This problem was solved by the invention of the integrated circuit
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Third Generation
3rd generation: ( ). Integrated Circuits.
Complete electronic circuit on single silicon chip, smaller than single transistor.
1000’s of components on one chip. (SSI to MSI)
cheap, fast and reliable.
used by small business
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Fourth Generation
4th generation: ( ). Microprocessors
Microprocessor contains ALL elements of CPU on one chip (Intel’s 4004, 1971).
Progressively greater integration (from LSI to VLSI) - 100,000’s to millions of components per chip.
Increasing
complexity of instruction sets,
no of bits handled at once,
amount of memory addressed.
Advent of personal computers and other microprocessor controlled devices.
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Fifth Generation
5th Generation:Ultra Large Scale Integrated Circuits (ULSI): over 1 million Transistors per Integrated Circuit or Chip
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26. Performance Enhancements
Computer performance has been greatly enhanced by the following :
Faster clock speed
Overlapping & Parallel instruction processing
Wider, faster data paths (Buses)
Faster disk access
Bigger and Faster memory, including advanced cache technology
Optimised software
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