Operating Systems

What is an Operating System?

The most important program on any computer is the Operating System or OS. The OS is a large program made up of many smaller programs that control how the CPU communicates with other hardware components. It also makes computers easier to operate by people who don't understand programming languages. In other words, operating systems make computers user friendly.

Do you remember ROM (Read Only Memory) and RAM (Random Access Memory) from Lesson 2? ROM and RAM are very important to the OS. Part of a computer's operating system is built into ROM. That part contains the most essential programs that the computer needs in order to run correctly. The ROM operating system is also known as the BIOS (Basic Input Output System). You may remember from Lesson 2 that the BIOS is responsible for waking up the computer when you turn it on to remind it of all the parts it has and what they do.

The operating system also contains other programs that are important, but not essential to making the computer run. The part of the operating system that contains these programs is stored on a computer's hard drive and is booted to RAM whenever the computer is turned on. This part of the operating system is known as DOS which stands for Disk-based Operating System.

Types of Operating Systems

Different computer manufacturers use different operating systems. Apple has specific operating systems for its line of Macintosh computers. When IBM released their Personal Computer or PC back in the early 1980's, they did not get a copyright on it, which allowed many other companies to build similar computers that were IBM-compatible; in other words, they used the same operating system as the IBM PC. There are different operating systems available for PCs, but the most common is Windows, which was developed by a company named Microsoft. Windows is similar to the Macintosh operating system, because it also uses a mouse and a GUI (Graphical User Interface) that uses graphics or pictures to help the user navigate within the computer system.

There are several versions of Windows (95, 98, NT, 2000), just as there are several versions of Macintosh operating systems (System 7, System 8). Operating systems are constantly being improved or upgraded as technology advances. When a company thinks that their operating system is now more advanced than the one already on the market, they release their new version for sale. Users can then purchase the new version and upgrade the part of the operating system that is stored on the hard drive. The ROM OS is not affected by the upgrade. Upgrading an operating system can have several advantages, such as simplifying tasks and navigation. However, there can be disadvantages, too. Many Windows 95 users upgraded to Windows 98 and discovered that many of their older programs would no longer run using the new operating system.

The Computer Revolution

The introduction of the Macintosh OS and the later introduction of Windows played a large part in making computers accessible to so many people. The user-friendly interfaces of both operating systems made it easier for people with no computer training to learn to use these amazing machines. Other machines, such as typewriters and payroll calculators quickly became a thing of the past, as computers became so easy to use and so affordable.