Introduction to Computers
Major Categories of Computers
These computers are regarded as the most powerful computers because of their large storage capacity and a high speed of execution. Most of these computers are developed to be used in sophisticated research project by scientists, for example, space exploration and engineers. The need for faster calculations in the scientific field has increased demand for supercomputers. A good example of the use of supercomputers is in the National Weather Bureau, in the United States, for conducting weather analysis for the whole world. Weather data from around the globe are collected for immediate analysis. Industries such as the airline industry rely heavily on such information hence the need for immediate analysis. Another application of the use of supercomputers is in geology where oil companies use the supercomputers to develop new strategies in geology. Analysis of geological data is normally complex and requires computers with a high speed of execution. In the car industry, the design of cars is normally simulated in supercomputers for safety analysis. This is because the safety analysis requires complex calculations during the simulation process.
Examples of supercomputers include the Jaguar supercomputer. This supercomputer has a 1.75 petaflop performance and utilizes 37,376 six-core AMD Istanbul processors (Miller, 2009). Another example of a supercomputer is the Nebulae that has Intel X5650 processors and Nvidia Tesla C2050 GPU. The Kraken is another example of a supercomputer that has an upgraded Cray XT5 system.
Mainframes
This is another category of computers. Mainframe computers are characterized with having large storage space and input-output devices. The increase in the number of input-output devices requires the mainframes to have more powerful processors. These types of computers are normally used by large organizations that have vast amounts of data to process. Mainframe computers can be able to connect input-output devices extending over large distances. Organizations such as banks located overseas that have a large customer base require mainframe computers to process data for their customer’s account. Customers bank account records are stored in the mainframe computers for access from any of the bank’s branches. Another application of mainframe computers is in the design of jets. Examples of mainframe computers include IBM zSeries, System z10 and System z9. IBM is one of the major manufacturers of mainframe computers.
Minicomputers
Minicomputers usually have more slots for input and output devices, and a larger storage capacity compared to microcomputers. Additionally, the speed of execution of minicomputers is higher than that of microcomputers. Minicomputers are normally used by large groups accessing data concurrently. This is possible since it is designed to support more devices and it has processors and support chips designed for accessing data concurrently. Minicomputers are expensive but have greater processing power than the microcomputers. Application of minicomputers is in large supermarkets where cash registers are connected to the same computer to send sales information. In factories, minicomputers are used to control automated assembly lines. Additionally, minicomputers are useful where many peripherals require to be connected such as in manufacturing plants. One of the downsides of minicomputers is that downtime means that organizations loses money. Examples of minicomputers include UNIVAC, NCR and Burroughs.
Microcomputers
Microcomputers have a distinct feature of having a single chip. This makes microcomputers affordable for a single user. Because of its affordability by a single person, it is sometimes referred to as the personal computer. The microcomputers can be produced in large quantities because of the low cost associated with producing computers on a single chip. Microcomputers are personalized to the level that they contain games and other features of entertainment for the user.
Microcomputers are further categorized into workstations, desktops, and servers. Workstations include those computers that are used for intensive work such as engineering designs. Desktops are used for business purposes and are normally placed on a desk physically.
Mobile Computers
These are computers that can be easily carried from one location to another. Examples include laptops and notebooks machines with the laptops being larger than the notebooks (Shelly, 2011).
Embedded computers
These are special-purpose computers that function as one component in a larger product. These types of computers perform diverse tasks based on the requirements of the product in which they are located (Shelly, 2011). Examples include digital cameras and mobile phones.
History of the Internet
Internet started in the 1970’s as ARPANET in the US department of Defense Advanced Research Projects Agency (ARPA). The purpose of ARAPNET was to enhance communication among the ARPA computer terminals since computers were expensive. ARAPNET developed because of the need to connect many computers for easier access of information by users without having to travel long distances. According to Shontell (2011), the internet became global in 1989 when Tim Berners-Lee created the World Wide Web. This was achieved through a successful communication between a server and a HTTP client. Subsequently Berners-Lee created the first web browser.
Physical Description
The Internet consists of a number of computers that are linked to each other all over the world. Communication is through satellite links and telephone wires that are connected by an Internet Protocol Suite. Once a computer connects to the internet it becomes part of a larger network. Normally computers can connect to a local area network (LAN) or a modem that connects to an ISP (Internet Service Provider). The ISP is connected to a larger network that connects to other networks located elsewhere globally. The Internet consists of clients and servers. A server is a machine that offers services to other machines, whereas clients utilize the services offered by the servers. This translates to the computer accessing the Internet as client with the internet being the Web server. To access information on the web server one needs to use a browser such as Firefox, which accesses information from Internet to bring up the requested information. This information is accessed through specific Internet Protocol Addresses and Uniform Resource Locators (URL). Internet Protocol (IP) Addresses are distinctive numbers that are allocated to each computer that accesses the internet. This allows the computer to communicate with each other. URLs represent addresses to specific information that is located on the World Wide Web (www). A collection of computers from various organizations that are linked together forms the Internet. The worldwide web comprises of information or electronic documents that are located via uniform resource locators (URLs).
Software
Software refers to programs used to operate computers. Software can either be system software, for example, operating systems and application software. Examples of operating systems include Windows 7, and Linux. These are categorized as system software. Operating systems can be used in business and home settings. Application software includes computer aided software such as AutoCAD that is normally used for business purposes. Application software such as the various players, for example, VLC is mostly used in home settings.
Components of the System Unit
According to Morley and Parker (2009), the system unit contains the processing hardware of the computer. Components of the system unit include ports and connectors, processor, expansion cards such as video card, sound card and network interface card, and a memory module. These components are connected together via a motherboard. A motherboard is a thin board containing computer chips and other electronic components (Morley & Parker, 2009). The computer chips include integrated circuits through which electrical circuits are carried in the motherboard. Another component of the system unit is the power supply that connects the computer to an electrical outlet. Drive bay is another component of the system unit in which storage devices can be secured. The central processing unit (CPU) is another component of the system unit that comprises of circuit components connecting it to the motherboard.
Input Devices
According to Godse and Godse (2007), input devices allow data, and various commands to be entered into a computer. One of the main input devices is the keyboard. The keyboard usually has different keys that are used to send distinct signals to the central processing unit. The normal keyboard has approximately 100 keys. Another key input gadget is the mouse. The purpose of the mouse is to assist in translational across the monitor. Computer mice use a variety of techniques for motion including the mechanical, inertial and optical sensors. Types of computer mice include optical mouse and the mechanical mouse. Light pen is an input device that functions as a drawing device when directed towards a computers screen. It functions in a similar manner as a touch screen, but with a greater level of positional accuracy (Godse & Godse, 2007). Light pens function only on CRT based monitors. A scanner is another input device that is used to store information in printed form for computer processing. Examples of scanners include sheet-fed scanners, drum scanners and handheld scanners.
According to Godse and Godse (2007), output devices can be categorized as either hardcopy devices or softcopy devices. One of the output devices is a monitor. The monitor is used to observe data processed from the central processing unit. A printer is a hardcopy device that is used to produce hardcopy output from a computer. In cases where the user needs to have sound output, the output devices used includes speakers or headphones.
Optical Storage Media
Optical storage media stores bit values as variations in light reflection (Burd, 2011). The optical storage medium surface consists of a highly reflective material. Compared to magnetic storages, optical storage media have a higher areal density and a longer data life (Burd, 2011). The recording densities are ten times higher than those for magnetic storage devices. DVDs and CD formats that are used for video and music recording are supported by optical storage devices.
How Optical Storage Media Works
The optical storage media uses reflected light to read data. The surface of the disk is covered with flat spots and tiny dents that change the way light is reflected. The read mechanism on the storage medium surface comprises of low-power laser and a photoelectric cell (Burd, 2011). The laser focuses on one bit location of the storage medium at a specific angle while the photoelectric cell is positioned differently to intercept the reflected laser light. The higher the reflection from the storage media surfaces the higher the chances of generating an electric current from the photoelectric cell. The generation of the current is interpreted as a binary of 1, and the lack of generation of the current is interpreted as 0.
Types of Optical storage Media
Types of optical storage media include compact disk read-only memory (CD-ROM), CD-Recordable (CD-R) and Digital Video Disk Read-Only Memory. Data on a CD-ROM is stored as a sequence of lands and pits along spiral tracks. The data are accessed or read by inserting the disk in a CD drive. The CD-ROM can store about 650MB of data. While rotating, laser beams senses pits and lands, which is converted to 1s and 0s by the photoelectric cell (Rajarman, 2003).
CDROM-Recordable
A laser beam is used to write data on a CDROM. The laser beam is turned on for writing a binary value of 1. This laser beam fuses with the reflective layer on the surface of the CDROM to form a pit. When the laser is off, the binary value of 0 is written forming the land. The CD reader correctly interprets the pits and lands in the CDROM.
DVDROM
A laser beam is used to record data on a DVDROM. However, the data on a DVDROM are recorded on two different layers on the disk. Since the wavelength of the laser beam is small, the pits generated are normally small. This allows for a greater amount of data to be recorded. DVDROM capacity is about 8.5 GB.
An example of software available for the challenged is the Quali-world. This software is used for accessing the computer without the conventional mouse and keyboard. The eye-tracking software is used for controlling the screen cursor by simple movement of the body. Speech recognition software allows operation of any application in the computer via speech. Hardware includes the Frog-pad, which is used by persons with one hand. Braille Embossers is another hardware device that is used for printing computer generated text in Braille format (Jagannathan, Raj& Gupta).
References
Caldwell, B., Cooper, M., Reid, L., & Vanderheiden, G. (2008, December 11). Web Content Accessibility Guidelines (WCAG) 2.0. World Wide Web Consortium (W3C). Retrieved July 10, 2012, from http://www.w3.org/TR/WCAG/
Miller, R. (2009, November 19). The Top Five Supercomputers, Illustrated » Data Center Knowledge. Data Center Knowledge » News and analysis about data centers, cloud computing, managed hosting and disaster recovery. Retrieved July 9, 2012, from http://www.datacenterknowledge.com/the-top-five-supercomputers-illustrated/
Jagannathan, S. Raj, P.G & Gupta, P.R. ICT for Physically Challenged Persons. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download doi=10.1.1.138.6622&rep=rep1&type=pdf
Morley, D., & Parker, C. S. (2010). Understanding computers: today and tomorrow (12th Ed.).
Boston, Mass.: Course Technology Cengage Learning.
Rajaraman, V. (2003). Introduction to information technology (Eastern economy Ed.). New Delhi: Prentice-Hall of India. SHELLY, G. B. (2011). Teachers discovering computers: Integrating technology in a connected World. New York: Cengage learning.
Shontell, A. (2011, June 27). What is the Internet, the history of the Internet, and how the Internet works - Business Insider. Business Insider. Retrieved July 9, 2012, from http://www.businessinsider.com/what-is-the-internet-and-how-the-internet-works2011-6?op=1
