introduction chapter 1. 1 history of computers development of computers began with many early...
TRANSCRIPT
Introduction
Chapter 1
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History of ComputersDevelopment of computers began with many early inventions:
The abacus helped early societies perform computations (c. 3000 B.C.)
The Pascaline used moveable dials to add numbers with up to eight digits (1642).
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Nineteenth-Century Inventions
The nineteenth century brought further inventions:
Charles Babbage’s Difference Engine and later his Analytical Engine defined many basic components of today’s computers.The arithometer (1820) performed four basic mathematical functions: + - * /.Herman Hollerith developed a system to aid in tabulating data from the 1890 U.S. Census using punch cards.
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First-Generation Computers
During World War II, the first generation of modern computers was introduced:
Colossus was developed in England to decode encrypted German messages.
ENIAC was developed in the U.S. to calculate ballistic missile trajectories.
EDVAC was designed by John Von Neumann and it featured a central processing unit.
UNIVAC was the first commercially available computing device.
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Second-Generation Computers
The second generation of computers (c. 1956) was marked by:
A shift from bulky vacuum tubes to transistors. A shift in programming from physically rerouting cables to “software” stored on punch cards and tape storage.The emergence of machine and assembly languages.
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Third-Generation Computers
With the invention of integrated circuits (ICs), computers became smaller and more powerful. ICs:
Are smaller than transistors
Produce less heat
Allow multiple components to fit on a smaller chip
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Fourth-Generation Computers
Computers became smaller and more affordable, and available to small businesses and individuals.
MITS Altair 8800 (1974)Apple I, IICommodore PETIBM PC (1981)Macintosh (1984)
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What is computer hardware?
Computer hardware are the physical components of the computer.
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Input/Output DevicesInput/Output devices provide communication between user and hardware.
Input DevicesKeyboard
Mouse
Scanner
Output DevicesMonitor
Speakers
Printer
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Processors and MemoryCentral Processing Unit (CPU)
Performs basic functions, millions and billions of times per second (brains of the computer)
Random-Access Memory Stores data used by the CPU (before and after processing)
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Data StorageData storage uses a variety of media. Capacity is measured in bits and bytes:
A bit represents the on or off state of a transistor (symbolized by a 1 or a 0).A byte is eight bits.A kilobyte is 210 or 1,024 bytes.A megabyte is 1,048,576 bytes.
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Hard DrivesThe hard drive is the primary storage device in a computer. Hard drives are:
Long term, rewritable storage
Large capacity
Inexpensive
Fixed media (relatively difficult to move from one computer to another)
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Removable MediaSome storage devices are more portable:
CD/DVDMedium capacity
Inexpensive
Easy to transport from one computer to another
Flash, Zip, USB drivesDiffering capacities
Differing price per MB
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Computer SoftwareSoftware can be divided into two categories:
Systems software includes operating systems, compilers, and utilities.
Application software runs on top of an operating system.
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What is an operating system?
An operating system (OS) manages the hardware and software on a computer system. An OS:
Manages memory and hardware resources
Allocates resources to applications
Provides a consistent interface for applications
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Operating SystemsUNIX/Linux
Multiuser OSMultitaskingRuns on many types of hardwareModular tools
Mac OSFirst mainstream graphical user interfaceIcons (pictures) and mouse replaced command line interface
DOS/WindowsDOS gained popularity with first PCsWindows provided graphical interface to DOSWindows later separated itself from DOS underpinnings
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ApplicationsDesktop Software
Installed on single computer
Most common type of application in use today
Web-Based SoftwareRuns on a Web server, accessed through a browser
Accessible anywhere one has access to the Internet
Web ServicesAllow applications to communicate with each other without user intervention
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Low-Level LanguagesLow-level programming languages use simple commands to communicate with the CPU:
Machine language (most basic language of the CPU)
Assembly language (human readable, but close to machine language)
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High-Level LanguagesHigh-level languages can be procedural or object-oriented:
Procedural languages use a step-by-step process to solve a problem.
Basic, Pascal, C
Object-oriented languages model problems using objects that correspond to real-world counterparts.
Smalltalk, C++, Java
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Software Development Process
Software development usually follows these basic steps:
Analysis DesignImplementationTestingDeploymentMaintenance