|Uses of a personal computer
Like other computers, personal computers can be instructed to perform a variety of individual functions. A set of instructions that tells a computer what to do is called a program. Today, more than 10,000 application programs are available for use on personal computers. They include such popular programs as word processing programs, spreadsheet programs, database programs, and communication programs.
Word processing programs are used to type, correct, rearrange, or delete text in letters, memos, reports, and school assignments. Spreadsheet programs enable individuals to prepare tables easily. The users of such programs establish rules for handling large groups of numbers. For example, using a spreadsheet program, a person can enter some numbers into a table and the program will calculate and fill in the rest of the table. When the user changes one number in the table, the other numbers will change according to the rules established by that user. Spreadsheets may be used for preparing budgets and financial plans, balancing a chequebook, or keeping track of personal investments.
Database programs allow a computer to store large amounts of data (information) in a systematic way. Such data might include the name, address, telephone number, salary, and starting date of every employee in a company. The computer could then be asked to produce a list of all employees who receive a certain salary.
Communication programs connect a personal computer to other computers. People can thereby exchange information with one another via their personal computers. In addition, communication programs enable people to link their personal computers with databanks. Databanks are huge collections of information stored in large centralized computers. News, financial and travel information, and other data of interest to many users can be obtained from a databank.
Other programs include recreational and educational programs for playing games, composing and hearing music, and learning a variety of subjects. Programs have also been written that turn household appliances on and off. Some people develop their own programs to meet needs not covered by commercially prepared programs. Others buy personal computers mainly to learn about computers and how to program them.
|COMPUTERS IN ASTRONOMY
Using computers is an important part of modern astronomy. Computers aid observational astronomers in many ways. For example, computers guide telescopes, and they control devices that measure the radiation gathered by telescopes. Astronomers also use computers to work out designs for new telescopes and to analyse data collected with telescopes. Computers have a major role in theoretical studies. A theoretical astronomer might use a computer to produce a mathematical model of the history of a star from its birth to its death.