Types of Operating Systems Within the broad family of operating systems, there are generally four types, categorized based on the types of computers co mputers they control and the sort of applications they support. The categories are: •
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Real-time operating system (RTOS) - Real-time operating systems are used to control machinery, scientific instruments and industrial systems. An RTOS typically has very little user-interface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time, every time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having hav ing it not move at all b because ecause the system is busy. Single-user, single task - As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern mode rn singleuser, single-task operating system. 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 MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it's entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message. Multi-user - A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The o perating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS and mainframe operating systems, such as MVS , are examples of multi-user operating systems.
Photo courtesy Apple
Mac OS X Panther screen shot
It's important to differentiate between multi-user operating systems and single-user operating systems that support networking. Windows 2000 and Novell Netware can each support hundreds or thousands of networked users, but the operating systems themselves aren't true multi-user operating systems. The system administrator is the only "user" for Windows 2000 or Netware. The network support and all of the remote user logins the network enables are, in the overall plan of the operating system, a program being run by the administrative user. With the different types of operating systems in mind, it's time to look at the basic functions provided by an operating system.
Real-time Operating System: It is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based of their priorities while time-sharing operating systems switch tasks based on clock interrupts. Multi-user and Single-user Operating Systems: The operating systems of this type allow a multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a
multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system. Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run at a time, the system is grouped under a single-tasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types namely, pre-emptive or co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. MS Windows prior to Windows 95 used to support cooperative multitasking. Distributed Operating System: An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each eac h other, gave rise to d istributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system. Embedded System: The operating systems designed for being used in embedded computer systems are known as embedded operating systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE, FreeBSD and Minix 3 are some examples of embedded operating op erating systems.
The operating systems thus contribute to the simplification of the human interaction with the computer hardware. They are responsible for linking application programs with the hardware, thus achieving an easy user access to the computers.
computer would be useless. Operating system types As computers have progressed and developed so have the types of operating systems. Below is a basic list of the different types of operating systems and a few examples of operating systems that fall into each of the categories. Many computer operating systems will fall into more than one of the below categories.
GUI - Short for Graphical User Interface, a GUI Operating System contains graphics and icons and is commonly navigated by using a computer mouse. See our GUI our GUI dictionary definition for a complete definition. Below are some examples of GUI Operating Systems.
System 7.x Windows 98 Windows CE Multi-user - A multi-user operating system allows for multiple users to use the same computer at the same time and/or different times. See our multi-user our multi-user dictionary definition for a complete definition for a complete definition. Below are some examples of multiuser operating systems.
Linux Unix Windows 2000 Multiprocessing - An operating system capable of supporting and utilizing more than one computer processor. Below are some examples of multiprocessing operating systems.
Linux Unix Windows 2000 Multitasking - An operating system that is capable of allowing multiple software processes to run at the same time. Below are some examples of multitasking operating systems.
Unix Windows 2000 Multithreading - Operating systems that allow different parts of a software program to run concurrently. Operating systems that would fall into this category are:
Linux Unix Windows 2000 Types of Operating systems
Within the broad family of operating systems, there are generally four generally four types, types, categorized based on the types of computers co mputers they control and the sort of applications they support. The broad categories are:
Real-time operating systems: They are used to control machinery, scientific instruments and industrial systems . An RTOS typically has very little user-interface capability , and no end-user utilities , since the system will be a sealed box when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time every ev ery time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having it not move at all because the system is busy.
Single-user, single-tasking operating system: As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm O.S. for Palm handheld computers is a good example of a modern single-user, single-task operating system.
Single-user, multi-tasking operating system: This is the type of operating system most people use on there desktop and laptop computers today. Windows 98 and the Mac O.S. are both examples of an operating system that will let a single user has several programs in operation at the same time. For example, it's entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message.
Multi-user operating systems: A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS, and mainframe operating systems , such as MVS, are examples of multi-user operating systems. It's important to differentiate here between multi-user operating systems and single-user operating systems that support networking. Windows 2000 and Novell Netware can each support hundreds or thousands of networked users, but the operating systems themselves aren't true multi-user operating systems. The system administrator is the only user for Windows 2000 or Netware. The network support and the entire remote user logins the network enables are, in the overall plan of the operating system, a program being run by the administrative user .
