Software System—Operating System Software and Application Software
The two different types of software programs are (1) operating system software and (2) application software. The diagram below illustrates the levels of interaction among users, application software, operating system software, and the hardware system.
Figure 4 Interaction among hardware system, operating system software, application software, and users
The operating system software serves as the interface between application software and the hardware components. And, the application software interfaces with the users of the computer system.
Operating system software provides instructions to hardware system components. Examples of operating systems are the Microsoft Windows operating system and the Macintosh operating system. When an input is entered, the operating system program provides instructions to send the input to appropriate hardware components for processing. Then, it provides instructions for the result to be sent to the appropriate output device. For example, when a user types using a keyboard, the Microsoft Windows operating system takes the input sent through the keyboard and displays the typed letters on the monitor. You will learn more about how operating system software works in Unit 3. Operating System Software.
Application software provides instructions that enable the user to perform specific tasks such as creating presentations, composing written documents, and editing images. Examples of application software programs are Microsoft Word and Notepad. Application software instructions are handled by the operating system. For instance, when you open a file using Microsoft Word, first the application provides the user-interface for you to specify which file you want to open (for example, the menu bar). Once you have selected the file, the application notifies the operating system that a certain file is needed. The operating system then requests for the file from the hard drive of the computer. You can view the application software currently on your computer by clicking on the Start button and select Programs. If you are reading this page online, then you are probably using the Internet Explorer or Netscape web browser program. More about how application software works will be discussed in Unit 4. Application Software.
Network System
The worldwide system of computer networks is the Internet, a network of networks. Via the Internet, computers on the network can access other computers on the network. The Internet allows data to be moved from one computer to another.
The network system manages how data is transferred from one computer to another and how different components of a network system work together. The diagram below illustrates the network components needed for a computer to communicate to other computer via the Internet.
Figure 5 Network connection components
A network interface card (NIC) sends data from a computer over a network, and collects incoming data sent by other computers. A modem is a device that enables data from a computer to be transmitted via phone lines or television cable lines to reach other computers on the Internet. In addition to these hardware network components, a computer also needs an Internet service provider such as America Online to enable its connection to the Internet. Application software such as Web browsers (for example, Internet Explorer and Netscape) and electronic mail (for example, Outlook and Netscape Mail) also enhance the usefulness of a network system. More about how the network system works will be discussed in Unit 5. Network Systems.