Information Technology Basics

19.31 Hasyim Asyari 0 Comments

• A computer system consists of hardware and software components.
• Hardware is the physical equipment such as the case, floppy disk drives, keyboard, monitor, cables, speakers, and printers.
• Software describes the programs that are used to operate the computer system. Computer software, also called programs, instructs the computer on how to operate.

• The two types of software are operating systems and applications.
• Application software accepts input from the user and then manipulates it to achieve the output.
• Examples of applications include word processors, database programs, spreadsheets, web browsers, web development tools, and graphic design tools.
• An Operating System (OS) is a program that manages all the other programs in a computer. It also provides the operating environment with the applications that are used to access resources on the computer.
• Examples of operating systems include The Disk Operating System (DOS), Windows 98, Windows 2000, Windows NT, Linux, Mac OS X, DEC VMS, and IBM OS/400.
• Operating systems are platform-specific.
• The Windows operating system (3.1, 95, 98, 2000, or NT) is designed for use with a PC.
• The Mac OS will only work with Macintosh computers.
• PC and Macintosh are called platforms. A platform is the computer system on which programs can run.

• There are two computer types, Mainframes and PCs.
• Mainframes are powerful machines that allow companies to automate manual tasks, shorten the time to market for new products, and run financial models that enhance profitability, etc.
• The mainframe model consists of centralized computers. End users interface with the computers via "dumb terminals". These dumb terminals are low cost devices that usually consist of a monitor, keyboard, and a communication port to talk to the mainframe.
• At its peak in the late 70s and early 80s, the mainframe market was dominated by IBM and Digital Equipment Corporation. These high-powered machines, however, came with high price tags.
• Advantages of mainframes:
  • Scalability, the ability to add more users as the need arises
  • Centralized management, Centralized backup
  • Low cost desktop devices (dumb terminals)
  • High level of security
• Disadvantages of mainframes:
  
  • Character based applications
  • Lack of vendor operating system standards and interoperability in multi-vendor environments
  • Expensive, with a high cost for set up, maintenance, and initial equipment
  • Potential single point of failure (non-fault tolerant configurations)
  • Timesharing systems, which means that there is a potential for a bottleneck
  • With the Personal Computer (PC), the Graphical User Interface (GUI) gained wide introduction to users.
  • As PC technology has improved, the power of the PC has risen to the point that it can perform enterprise level functions.
• Advantages of PC computing:
  • Standardized hardware
  • Standardized, highly interoperable operating systems
  • GUI interface
  • Low cost devices (when compared to mainframes), low cost of entry
  • Distributed computing
  • User flexibility
  • High productivity applications
• Disadvantages of PC computing:
  
  • Desktop computers cost, on average, five times as much as dumb terminals
  • No centralized backup
  • No centralized management
  • Security risks can be greater (physical, data access, and virus security)
  • High management and maintenance costs, although they are generally cheaper to maintain than mainframes
• Disadvantages of PC computing:
  
  • Desktop computers cost, on average, five times as much as dumb terminals
  • No centralized backup
  • No centralized management
  • Security risks can be greater (physical, data access, and virus security)
  • High management and maintenance costs, although they are generally cheaper to maintain than mainframes
  
  

• A PC is a standalone device, meaning that it is independent of all other computers.
• Businesses, government offices, and schools need to exchange information and share equipment and resources. To do this, a “networking” was developed to connect computers.
• A network is simply a group of computers that are connected so that their resources can be shared.
• Networks are not limited to just a building or school campus. Networks can be an entire school district or all of the offices in a company.
• A school, for example, is connected to a main district office, as are all the other schools in a district.
• The Internet is the ultimate network, connecting millions of smaller networks.
• Most connections are made by cable, but wireless connections are beginning to gain popularity. Cable can carry voice, data, or both.
• Homes may have modems that plug into telephone jacks. The telephone line carries voice signals when the telephone is plugged into the jack, but carries data signals (encoded to appear as if they were voice) when the modem is connected.
• Other faster connections to the Internet are available, such as Digital Subscriber Line (DSL), cable, and T1, T3, or E1 lines.

• In the 1960s, the U.S. Department of Defense (DoD) recognized the need to establish communications links between major U.S. military installations.
• The motivation was to maintain communications if a nuclear war resulted in the mass destruction and breakdown of traditional communication channels.
• Throughout the 1970s, more nodes or access points were added, both domestically and abroad.
• In 1983 the ARPANET was split, and Military Network (MILNET), which was integrated with the Defense Data Network (DDN), took 68 of the 113 existing nodes.
• The DDN had been created the previous year. The Domain Name System (DNS) was introduced in 1984, providing a way to map "friendly" host names to IP addresses.
• In 1984, there were more than 1,000 host computers on the network.
• During the last half of the 1980s the National Science Foundation (NSF) created supercomputer centers in the United States at Princeton, the University of California, the University of Illinois, and Cornell University.
• The Internet Engineering Task Force (IETF) was also created during this time.
• By 1987, there were 10,000 hosts on the network, and by 1989, that number increased to over 100,000.
• In 1990 ARPANET evolved into the Internet.
• The National Science Foundation Network (NSFNET) backbone was upgraded to T3 speed (that is, 44.736 Mbps)
• The Internet Society (ISOC) was formed, and in 1992 more than 1 million hosts existed on the Internet.
• By 1995, online advertising had caught on, online banking had arrived, and even a pizza could be ordered over the Internet.
• In the late 1990’s, streaming audio and video, "push" technologies, and Java and ActiveX scripting took advantage of higher performance connectivity that was available at lower and lower prices.
• Today, there are millions of sites that exist on the World Wide Web, with millions of host computers participating in this great linking.

• The cost of the increasingly sophisticated technology has fallen.
• For under $1,000 users can buy a computer system that is capable of doing much more, and doing it better and faster than the $500,000 mainframe version of 20 years ago.
• Internet access at speeds equivalent to T1 is available through Digital Subscriber Line (DSL) or cable modem for U.S. $30 to $40 per month, and prices are falling.