Information Systems Theory

Chapter 1: An Overview of Using Computers



This chapter introduces several concepts associated with computer systems. The objectives important to this chapter are:

  1. The information processing cycle
  2. Elements of an information system and hardware components
  3. Size categories of computers
  4. Software development/computer personnel



The chapter opens with a discussion of two concepts:

  • Computer literacy - knowledge of how to use a computer
  • Information literacy - knowledge about how to find, analyze, and use information

Computers are defined as electronic devices that perform four functions:

  • input - the computer must be given instructions, or data to work on, often by a user using a mouse or a keyboard
  • processing - the computer must be able to do something with the data. (Some books define processed data as information.) This is performed by the Central Processing Unit (CPU).
  • output - the processing generally produces a result that is given to the user as output, usually on a screen or a printer
  • storage - all computers have temporary storage ability. They are able to store data until it can be processed. Most computers can also access some kind of "long term" storage. The difference is often that temporary storage is emptied when the computer is turned off, while long term (or "permanent") storage is not.

The four functions above are called the information processing cycle.

The text offers a justification for using computers. They are faster, more reliable, and more accurate than a human being doing the same tasks. They are better at repetitive tasks than humans, who become bored by repetition.

A chart appears on page 1.10, showing descriptive properties of five types of computers. You should be familiar with this chart, but you should also be aware that it is dated. The column about speed is least informative, since the speed of computer processors changes daily.

The five categories listed are:

  • personal computer - affordable for most people, can be networked or used as a stand alone system
  • server - used to provide services on networks
  • minicomputer - often a server, perhaps dedicated to a high end task
  • mainframe - meant to be used by many users simultaneously, such as users dialing in to an online service
  • supercomputer - very expensive, often used for very complex calculations, such as weather prediction, and aerodynamic design

So far, we have been discussing hardware. Software is a conceptual thing. Software is another name for a program, which is a series of instructions that tell the computer to do something. There are many levels of complexity to writing computer programs. Practically anyone can save a series of commands in a file and learn to tell the computer to run that program. A professional computer programmer should be capable of creating a program that is useful and pleasant to use. A systems analyst may be required to give a programmer guidance in creating a more complex program.

Three levels of software are discussed:

  • operating system software - this interacts with the hardware at a very basic level, and is necessary to provide basic services to the user, such as saving and retrieving files
  • user interface - The user may issue commands to either the operating system or an application through an interface, an environment that makes it easier to use. The most common user interface is a Graphic User Interface (GUI), such as Microsoft Windows. (Exception: Windows NT and Windows 2000 are actual operating systems, not just interfaces.)
  • application software - there are many kinds of applications, which are programs that perform a specific kind of task for the user. All applications interact with the operating system software through a user interface.

An information system may be described as the path information flows through in company. Whether the information is stored and used on paper or on computers, it is still an information system. Computer based information systems are usually superior to those without computers.