Operating System

2.1 About Operating System

Operating system is the first software that we see when we turn on the computer, and the last time we see when we turn off the computer. Many users don’t know what it is that the operating system does precisely. It has requirement for software to be called an operating system. We will discuss how operating system works to turn a collection of hardware to be a powerful tool.

2.2 How it Works [2]

Not all of computers have an operating system. Let’s have a look at Auto Teller Machine (ATM). It has one simple task to perform. With its input and output, and unchanged hardware to control, it doesn’t need an operating system to add more complexity into a simply single program.

For computer systems that more complex that an ATM, it need operating system that can be the key to make easier application development, and more efficiency.

There are hundreds of operating systems available for special-purpose application, but most commonly use in desktop computer is Windows family, UNIX family, and Macintosh. We will discuss about those 3 operating systems more deeply later on.

Generally, operating system does two things:

1. It manages the hardware and software resources of the computer system. It include such as processor, memory, storage, etc.

2. It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.

Even if a particular computer is unique, an operating system can ensure that applications continue to run when hardware upgrades and updates occur. This is because the operating system is charged with managing the hardware and the distribution of its resources. One of the challenges facing developers is keeping their operating systems flexible enough to run hardware from the thousands of vendors manufacturing computer equipment. Today's systems can accommodate thousands of different printers, disk drives and special peripherals in any possible combination.

2.3 KINDS OF OS [2]

There are generally four types, categorized based on the types of computers they control and the sort of applications they support:

• Real Time Operating System (RTOP) - Real-time operating systems are used to control machinery, scientific instruments and industrial systems.

• Single User, Single Task - this operating system is designed to manage the computer so that one user can effectively do one thing at a time.

• Single User, Multi-tasking - This is the type of operating system most people use on their desktop and laptop computers today. Microsoft's Windows and Apple's Mac OS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time.

• Multi User - A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously.

2.4 OS Tasks

The operating system's tasks, in the most general sense, fall into six categories: [2]

• Processor management - Ensuring that each process and application receives enough of the processor's time to function properly. And using as many processor cycles