accc.docx

LESSON 3: COMPUTER ENVIRONMENT 1: Mainframe Computing 2: Network Computing 3: Internet --------------------- MAINFRAME COMPUTING --------------------- - many people share access to a mainframe computer -------------------- INFORMATION SYSTEM -------------------- - combination...

LESSON 3: COMPUTER ENVIRONMENT 1: Mainframe Computing 2: Network Computing 3: Internet --------------------- MAINFRAME COMPUTING --------------------- - many people share access to a mainframe computer -------------------- INFORMATION SYSTEM -------------------- - combination of information, technology, processes, and people brought together to support a given business objective ------------------- NETWORK COMPUTING ------------------- - an organization has linked together personal computers that have been connected into a network ---------------------------- TYPES OF COMPUTER NETWORKS ---------------------------- +-----------------------------------------------------------------------+ | 1: LAN (LOCAL AREA NETWORK) | +=======================================================================+ | - a computer network located within a limited area such as | | building, agency, university or campus | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 2: WAN (WIDE AREA NETWORK) | +=======================================================================+ | - a computer network that covers a large geographical area | +-----------------------------------------------------------------------+ ---------------------- STAND ALONE COMPUTER ---------------------- - computer connected to a network ------------- WORKSTATION ------------- - two or more computers are physically connected to each other in a local area network using cables or other communication channel ---------------- NETWORK SERVER ---------------- - computer connected to a network that "serves" or distributes resources to network users ------------- FILE SERVER ------------- - computer that serves or distributes application programs and data files to workstations within a computer network - the hard drive of the file server is shared by the workstations on the network -------------------- APPLICATION SERVER -------------------- - computer that runs applications software and runs the results of processing to workstation as required --------------- CLIENT/SERVER --------------- - there is a host computer which is the server and there are other computers which serve as the clients ---------- INTRANET ---------- - internal computer network that belongs to an organization and is accessible only by tat organization's members ----------------- BEFORE INTERNET ----------------- - each network is autonomous ------------------------------- SHORT HISTORY OF THE INTERNET ------------------------------- 1: ARPANET 1969 Stanford Research Institute (SRI) 2: University of California at Santa Barbara 3: University of Utah\ 4: University of California at L.A. (UCLA) +-----------------------------------------------------------------------+ | 1972 | +=======================================================================+ | - First application of e-mail | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1978 | +=======================================================================+ | - Gary Thuerk sends what is widely considered to be the first spam | | message | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1982 | +=======================================================================+ | - Scott Fahlman kick-starts smiley-culture by suggesting using the | | :-) and :-( smileys to convey emotions in emails | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1988 | +=======================================================================+ | - Robert Morris: First internet worm is released | | | | - it infects about 6000 computer | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1989 | +=======================================================================+ | - Tim-Berners Lee and the team CERN invented WWW (World Wide Web) | | | | - WWW: to make information easier to publish and access in the | | internet | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1995 | +=======================================================================+ | - Jerry and David founded Yahoo | | | | - at first it received 100,000 visitors, it displays adverts | | | | - DEC (Digital Equipment Corporation) Research launches AltaVista | | which it claims can store and index the HTML from every internet | | page | | | | - Jeff Bezos launches Amazon (an online bookseller that pioneers | | e-commerce) | | | | - Ebay is launched to enable internet users to trade with each | | other | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1996 | +=======================================================================+ | - Macromedia Flash 1.0 launches **Adobe Flash** to add interactive | | animation to web pages | +-----------------------------------------------------------------------+ +-----------------------------------------------------------------------+ | 1998 | +=======================================================================+ | - Google arrives | +-----------------------------------------------------------------------+ ---------- INTERNET ---------- - collection of local, regional, and national computer networks that are linked together to exchange data and distribute processing tasks - Internet collects millions of people through a collection of computer networks ---------------- WORLD WIDE WEB ---------------- - a computer network system that allows users to browse through information available on computers around the world - a web page might also contain one or more links that points to other web pages - every web page is stored as an HTML (HyperText Markup Language) document - LINK: - a reference to another document in an environment like the WWW, that users can go directly by clicking on the 0n-screen reference with the computer's mouse -------------------------------- URL (UNIFORM RESOURCE LOCATOR) -------------------------------- - global address of documents and other resources on the WWW - URL's can point to executable files that can be fetched using FTP (File Transfer Protocol ftp//) or a web page that can be retrieved using HTTP (Hypertext Transfer Protocol http://) - after the http:// the next segment of the address is the server name - The server is the computer and the software that make the data available - Web Server: is a computer that uses Web Server software that transmit Web Pages over the Internet - Most Web Servers have domain names prefixed with WWW. By entering Web Server name, one accesses the site's home page -------------------------------- URL (UNIFORM RESOURCE LOCATOR) -------------------------------- - main page of a website - serves as an index or table of contents to other documents stored at the site (the address) --------- WEBSITE --------- - location on the WWW --------------- SEARCH ENGINE --------------- - a program that searches documents for specific keywords and returns a list of documents where the keywords were +-----------------------------------------------------------------------+ | LESSON 4: | | | | HOW DOES A COMPUTER WORK | +-----------------------------------------------------------------------+ --------------------------------------- A COMPUTER FUNCTIONS IN THE FF MANNER --------------------------------------- - The computer accepts input - The computer performs useful operations - The computer stores data - The computer produces output ---------------------------- THE COMPUTER ACCEPTS INPUT ---------------------------- ---------------- COMPUTER INPUT ---------------- - whatever is entered or fed into a computer system Input can be supplied: - By a person (using a keyboard) - By another computer or device (such as CD-ROM or USB) Examples of Input: - Words and Symbols in a document - Numbers for calculation - Instructions for completing a process, - Pictures ----------------------------------------- THE COMPUTER PERFORMS USEFUL OPERATIONS ----------------------------------------- --------- PROCESS --------- - a systematic series of actions a computer uses to manipulate data - computer process data in the CPU Examples or Process: - Performing Calculations - Sorting lists of words or numbers - Modifying documents and pictures according to user instructions - Drawing graphs -------------------------- THE COMPUTER STORES DATA -------------------------- - computer must store data so that it is available for processing - most computers have more than one location for storing data (hard drive, USB, CD-ROM) - the place where the computer stores data depends on how data is being used - the computer puts the data in one place while it is waiting to be processed and another place when it is not needed for immediate processing - Online Storage - the storage of data in the computer - Offline Storage - storage of data on computer tapes, diskettes, CD-ROM, or USB ------------------------------ THE COMPUTER PRODUCES OUTPUT ------------------------------ ----------------- COMPUTER OUTPUT ----------------- - information that produced by a computer - Output can be in several different forms such as paper, diskette, or on screen - Examples of Computer Output - Reports - Documents - Music Graphs - Pictures ----------------------------------------- HOW DOES A COMPUTER PROCESS INFORMATION ----------------------------------------- - when a data is input into a computer, the number of words we understand are translated into a binary number system -------- BINARY -------- - everything you type, input, output, send, retrieve, draw, and so on, in the end, converted to the computer's native language ---------------------- BINARY NUMBER SYSTEM ---------------------- - numerical system wherein each digit stand for a power of two - uses only two symbols, 0 and 1, to represent values ----- BIT ----- - a digit within a binary number system - smallest unit of information held in a computer ------- BYTES ------- - a combination of bits that represent one character - usually composed of 8 bits Kilo 1,000 (thousand) ------ -------------------------------- Mega 1,000,000 (million) Giga 1,000,000, 000 (billion) Tera 1,000,000, 000, 000 (trillion) 1 bit 1 or 0 ---------------- -------------------------------------- 8 bits 1 byte (B) (combination of 1s or 0s) 1024 bytes 1 kilobytes 1024 kilobytes 1 megabytes 1024 megabytes 1 gigabytes 1024 gigabytes 1 terabyte (TB) Bits is represented by "b" Kb = Kilobits Bytes is represented by "B" KB = Kilobytes