Multi-User Operating Systems
Multi-user operating systems (OS) are designed to allow multiple users to access and interact with a single computer system simultaneously. This is achieved through networked terminals connected to a central mainframe, which manages the processing requests from each user in a way that appears seamless and synchronous. Unlike single-user OSs, where only one user can operate the machine at any given time, multi-user OSs handle multiple user requests through time-sharing, allowing the system to allocate brief processing intervals to each user in rapid succession.
Historically, multi-user OSs emerged during the early days of computing when large, complex machines were shared by many users. As computers evolved, the design philosophy retained the idea of shared access, leading to the development of early systems like UNIX. Today, multi-user OSs are crucial for environments that require support for numerous simultaneous users, such as webmail servers, which can facilitate millions of logins at once.
Organizations are increasingly adopting multi-user OSs to optimize costs, as this model allows them to utilize less powerful terminals while centralizing data and management on dedicated servers. This approach not only reduces hardware costs but also simplifies data backup processes, ensuring greater data security and efficiency in organizational operations.
Multi-User Operating Systems
- FIELDS OF STUDY: Computer Science; Operating Systems
ABSTRACT
A multi-user operating system (OS) is one that can be used by more than one person at a time while running on a single machine. Different users access the machine running the OS through networked terminals. The OS can handle requests from users by taking turns among connected users. This capability is not available in a single-user OS, where one user interacts directly with a machine with a single-user operating system installed on it.
Multi-User Operating Systems
A computer's operating system (OS) is its most fundamental type of software. It manages the computer system (its hardware and other installed software). An OS is often described as the computer's "traffic cop." It regulates how different parts of the computer can be used and which users or devices may use them. Many OS functions are invisible to the user. This is either because they occur automatically or because they happen at such a low level, as with memory management and disk formatting.
A multi-user OS performs the same types of operations as a single-user OS. However, it responds to requests from more than one user at a time. When computers were first developed, they were huge, complex machines that took up a great deal of physical space. Some of the first computers took up whole rooms and required several people to spend hours programming them to solve even simple calculations. These origins shaped the way that people thought about how a computer should work. Computers became more powerful and able to handle more complex calculations in shorter time periods. However, computer scientists continued to think of a computer as a centralized machine usable by more than one person at a time through multiple terminals connected by networking. This is why some of the earliest OSs developed, such as Unix, were designed with a multi-terminal configuration in mind. Given the nature of early computers, it made more sense to share access to a single computer. Only years later, when technology advanced and PCs became widely available and affordable, would the focus switch to single-user OSs.
Shared Computing
For an OS to serve multiple users simultaneously, the system must have multiple processors that can be devoted to different users or a mechanism for dividing its time between multiple users. Some multi-user OSs use both strategies since there is a point at which it becomes impractical to continue adding processors. A multi-user OS may appear to be responding to many different requests at once. However, inside the machine, the computer is actually spending a very small amount of time on one task and then switching to another task. This is called time-sharing. This task switching continues at a speed too fast for the user to detect. Therefore, it appears that separate tasks are being performed at once. Multi-user OSs function this way because if they handled one task at a time, users would have to wait for their requests to be filled. This would be inefficient because users would be idle until their requests had been processed. By alternating between users, a multi-user OS reduces the time spent waiting. Time-sharing is one aspect of resource allocation. This is how a system's resources are divided between the different tasks it must perform.
One example of a multi-user OS is the software used to run the servers that support most webmail applications. These systems have millions or even billions of users who continually log on to check their messages, so they require OSs that can handle large numbers of users at once. A typical webmail application might require hundreds of computers, each running a multi-user OS capable of supporting thousands of users at once.
Economy of Scale
Many companies are moving back toward the use of multi-user OSs in an effort to contain costs. For a large organization to purchase and maintain full-featured computers for each employee, there must be a sizable investment in personnel and computer hardware. Companies seeking to avoid such expenses find that it can be much more cost effective to deploy minimally equipped terminals for most users. This allows them to connect to servers running multi-user OSs. Backing up user data is also simpler with a multi-user OS because all of the data to be backed up is on the same machine. Therefore, it is less likely that users will lose their data, and it saves time and money for the organization.
Bibliography
Anderson, Thomas, and Michael Dahlin. Operating Systems: Principles and Practice. Recursive, 2014.
Garrido, José M, et al. Principles of Modern Operating Systems. Jones, 2013.
Holcombe, Jane, and Charles Holcombe. Survey of Operating Systems. 7th ed., McGraw, 2025.
"Multi-User Operating System." GeeksforGeeks, 19 Oct. 2022, www.geeksforgeeks.org/multi-user-operating-system. Accessed 6 Feb. 2025.
Silberschatz, Abraham, et al. Operating System Concepts Essentials. 2nd ed., Wiley, 2014.
Stallings, William. Operating Systems: Internals and Design Principles. 9th ed., Pearson, 2021.
Tanenbaum, Andrew S. Modern Operating Systems. 5th ed., Pearson, 2022.