Security Problems in Multiprogramming and Time-Sharing Environment
Multiprogramming is one of the more basic types of parallel processing that can be employed in many different environments. Essentially, multiprogramming makes it possible for several programs to be active at the same time, while still running through a single processor. The functionality of multiprogramming in this environment involves a continual process of sequentially accomplishing tasks associated with the function of one program, then moving on to run a task associated with the next program.
In multiprogramming, concurrent running (sharing of the processor) is achieved when the operating system identifies opportunities to interrupt the handling of one program between tasks (e.g., when it is waiting for input/output) and to transfer process control to another program (application, job or user). To a great extent, the ability of a system to share its resources equitably—or according to certain priorities—is dependent upon the design of the programs being handled and how frequently they may be interrupted.
On the other hand, time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major technological shift in the history of computing.
By allowing a large number of users to interact concurrently with a single computer, time-sharing dramatically lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one, and promoted the interactive use of computers and the development of new interactive applications.
In addition to that, several users share the system simultaneously. And this situation can result in various security problems. Two of these problems are (1) taking possession or copying another user’s data and (2) using system resources without proper accounting.
People could not avoid copying another user’s data but the problem in that situation is that there are times that the shared files is gained, often by devious means, by those who should not have access to them. Another thing is that, one user may use the resources or the copied data but charge expenses to other users.
The other dilemma concerning the security problems in multiprogramming and time sharing environment includes the usage of system resources without proper accounting. System resources are the parts within a computer that are available to be used by the operating system and other applications. Examples of these are CPU, amount of memory in use, printer, etc. Improper accounting would cause troubles such as; the printer could mix output by sending data while some other users file is printing.
On the other case, I don’t think that people can ensure the same degree of security in a time-share machine as we have in a dedicated machine. As we all know, a time sharing system or a server provides several people the opportunity to use the system. Technically, even a standard PC is a time-sharing system due to the fact that people can run numerous programs on it at the same time. Meanwhile, dedicated machine is a computer that services one primary function or task.
Since a time-share machine allows multiple users to use the system, there is a high risk on various security problems. However, there would be a possibility that the people can really ensure a security on dedicated machines since it only assist one task. Thus, the users could not manipulate several data.
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