chapter 1 the basics of computing what is a computer types of computers computer hardware computer...
TRANSCRIPT
Chapter 1
The Basics of Computing
• What is a Computer• Types of Computers• Computer Hardware• Computer Software• Communication Networks
What is a Computer?
Input ProcessingInstructions
Output
A computer is a device that accepts input, manipulates it under a sequence of instructions (a program) and produces an output. This process is called the “Information Processing Cycle.”
The output can be the result of a calculation or just an acknowledgement of the input.
For example…
…an abacus is a kind of computer…
However, we’re concerned with just 3 types of computers that are used for business information systems:
• Mainframes
• Minicomputers
• Microcomputers
Mainframe Computers
• industry term for a large computer“big iron”
• modularized to reduce overhead• used in centralized computing environments• large-scale computing server
• high volume• high overhead processing
• used as large database servers
Mainframes typically cost hundreds of thousands of dollars and are manufactured by companies such as Hitachi, IBM and Amdahl.
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Diagram of a Simple Mainframe Configuration
Minicomputers
• smaller than a Mainframe• larger than a PC (Microcomputer)• have become the “mid-range” server
• IBM’s AS/400 is an example
IBM AS/400
Microcomputers
• Personal Computers (PCs)• desktop computing and client-server applications• can serve both as a client and a server• are generally categorized by the CPU type
• Intel – IBM compatible• Motorola – Apple / MacIntosh / Power PC• Sun - SPARC
Microcomputers are what we think of as PCs. Although they cross the line at times, Sun Microsystems generally is thought to manufacture high-end PCs.
Basic Parts of a PC
MouseKeyboard
Computer Case
Monitor
Components of a Computer
A computer needs the following devices to function:
• Input device(s)• Processing Unit• Output device(s)• Storage device(s)
This is the computer’s hardware…it is tangible.
Input Devices
• Keyboard
• Mouse
• Scanner
• Microphone
Accept data for the computer to work with…
Processing Unit
The Central Processing Unit, or CPU, is the brains of the computer. It controls all activity and performs operations on data based on its instruction set. The CPU is made up of several major units as diagrammed below.
Processing Unit
The CPU consists of these main elements:
• Control Unit - executes the instructions as interpreted• Arithmetic / Logic Unit - performs mathematical and
logical operations• Registers - serve as the short term memory for
the ALU’s computations and provides somereserved space for certain functions
• Clock Unit - generates pulses that determine the speed of instruction processing, the rate is
measured in megahertz (Mhz)
Processing Unit
The CPU has two main features:
• Its speed measured in millions of instructions per second, or MIPS
• Its word size is the number of bits the CPU can process at a time. An 32-bit processor
manipulates 32 bits simultaneously.
System Memory
A PC has three basic types of memory:
• Cache memory that is built into the CPU (not the CPU registers) called L1 or L2 cache
• Read Only Memory (ROM) that is used to “boot” the system (among other applications)
• Random Access Memory (RAM) which is the main memory that acts like the workshop or
desktop of the CPU
Output Devices
The purpose of an output device is to present electronic data (and the results of our work) in a form that can be understood and used. For example, think how hard it would be to use a computer without a monitor.
Typical output devices on a PC are:• Monitor• Printer or Plotter• Speakers
Output Devices
Monitors:• CRT – Cathode Ray Tube, like a Television• LCD – Liquid Crystal Display• TFT – Thin-Film Transistor
Printers:• Laser printers• Inkjet• Thermal Wax• Dot-Matrix
Auxiliary Storage Devices
These devices, also known as secondary storage, are where the PC stores data that must last from session to session. Basically speaking this is the permanent data storage.
Though they differ in their technologies and methods of storage, the result is the same; the PC can easily retrieve the stored data for use at a later time.
These components are many times referred to as Mass Storage devices.
Auxiliary Storage Devices
Types of Auxiliary or Mass Storage devices are:
• Floppy disk drive • Hard disk drive • Optical disks (Compact discs, DVD)• Zip drives• Jazz or Bernoulli drives• Tape drives• Flash memory
Computer Software
Two general types of software:• System software• Application software
Software is computer instructions (Programs) and data. Anything that is electronically stored on a computer storage device is considered software.
It is intangible and exists only electronically.
System Software
Systems software are the programs that controlthe computer and manage its resources. Such asoperating systems and system utilities.
Operating systems perform the basic tasks of computing like managing the input and output of data and interpreting the instructions of the programs.
System Utility software performs more basic functions such as file management or backup, but they must work under an operating system.
O pe r at i ngSys te m
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The Operating system connects components and directs the flow of data.
System Software
Examples of Operating systems:• Windows (XP, 2000, ME, 98, 95, 3.1, CE)• DOS (MS-DOS, DR-DOS, PC-DOS)• Mac OS X• Unix (Solaris, FreeBSD, SCO UNIX)• Linux• Palm OS• BeOS
Operating systems are written to run on specific processors (platforms).
System Software
Examples of Utility software:• Anti-virus software
• Norton, McAfee, Sophos, Trend Micro• File Management
• PKZip, WinZip, Norton SystemWorks• Disk Utilities
• PartitionMagic, System Commander• Backup
• Retrospect, Backup MyPC
Utility software is written to run under specific operating systems.
Application Software
Application software consists of programs that help you work and play on the computer. This category includes word processors, games, spreadsheets, drawing and other “productivity”programs.
This is the bulk of all software written.
Application software is written to run under specific operating systems.
Application Software
Examples of Application software:• Document Processing
• Adobe Acrobat, WordPro, TextBridge• Graphics
• Flash, CorelDraw, PaintShop Pro• Games
• MS Flight Simulator, Tomb Raider• Programming
• Kylix, CodeWarrior• Suites
• StarOffice, WordPerfect Office, Office 2000• Database Management
• Oracle, SQL Server, MySQL
Communication Networks
aka Computer Networks
Two or more computers connected to share data and resources are “networked.” The simple idea behind computer networking is to allow users to access more information and give them access to devices not directly attached to their “local” system, such as printers or storage devices.
Computer Networks
Two of the main types of computer networks are:• LAN - Local Area Network• WAN - Wide Area Network
A LAN is comprised of computers located within close proximity, such as in an office or building. A WAN is a network of computers that are situated further apart, but still connected. Such a network might be of computers within a single state agency or of a multi-national corporation worldwide.
Computer Networks
A PC must have a Network Interface Card installed to connect it to a network. The cards, frequently called “nics”, come installed in many new computers as they are also used for cable modem and DSL internet service.
The computers can be configured in several ways, the most popular of these “architectures” are peer-to-peer and client/server. The first is a looseconnection of local computers with no central authority, the later relies on a “server” to manage the network and its resources.
A peer-to-peer network requires the computers to be connected to each other by a network cable, usuallyan “unshielded twisted pair” cable known as “CAT 5”. Connecting more then two computers require the use of a network hub as shown.
E th er n e t Hu b
P eer - to - P eer N etw o r k
A client/server network uses a computer known as the server to manage the network and control access to resources. The computers can be connected using various types of cable including CAT 5, coaxial and fiber optical.
C lien t/S er v er N etw o r k
N etw o r k S er v er
Hu b
Computer Networks
Local Area Networks are configured in 3 basic topologies. These are either the logical orphysical way the computers are connected. Each connection on the network is known as a node.
These topologies are:• Star• Bus• Ring
A Star topology connects all the nodes directly to the server or to a connecting device such as a hub.
S er v er
All nodes on a Bus topology are connected to acentral line or backbone.
S er v er
Nodes on a Ring topology are connected in a closed loop. This means that each node has two connections,one in and another out. Using this type of topology the data must travel through all the nodes.
S er v er
Computer Network Software
Computer networks use special operating systems and other system software to manage the network, its resources and its users. Network Operating Systems (NOS) should be very secure and robust to provide reliable network services.
Examples of such software are:• Windows 2000 Server• Novell NetWare• Unix…too many flavors to link them all• Linux
The Internet
The Internet is a worldwide computer network.Actually it is a loose collection of networks. There is no central control or authority, all cooperationis voluntary to a degree…
Users access the Internet by using a network that is connected to a “backbone” usually through an Internet Service Provider (ISP). The real accesspath to the ‘net is through a Network Access Point (NAP).
The World Wide Web
The World Wide Web is a collection of computers connected via the Internet that support the use of documents written in HyperText Markup Language(HTML). The “web” uses the HyperText Transfer Protocol (HTTP) as the standard for the formatting and transmission of these documents.
Not every server on the ‘net uses HTTP, andtherefore is not part of the Web.
The Internet is very large and diverse, there is no one method of access and there are many protocolsused such as:
• NNTP - Network News Transfer Protocol for newsgroups
• SMTP - Simple Mail Transfer Protocol for sending e-mail
• FTP - File Transfer Protocol used for sending files
It’s a wonder it works so well, much less at all.
Hobbes' Internet Timeline:http://info.isoc.org/guest/zakon/Internet/History/HIT.html