CASE STUDY # 3

In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. Name at least two of these problems. Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine? Explain your answer

Multiprogramming is a rudimentary form of parallel processing in which several programs are run at the same time on a uniprocessor. Since there is only one processor , there can be no true simultaneous execution of different programs. Instead, the operating system executes part of one program, then part of another, and so on. To the user it appears that all programs are executing at the same time.

One problem that could occur is that one user may modify the data which is required by another user. For example, User A is saving a data in the CPU, and User B is browsing some files and unintentionally modified the file that User A is doing, it could ruin the files of which User A is doing and it could end up in a mess. Another example is that when User A is decrypting a data that very important and private, but User B intentionally removes the data or is decrypting also the data at the same time. This could lead into a certain mislead action and is possibly a dangerous one.

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. Dedicated Machine is a computer that services one primary function or task. For example, an automobile might have an onboard computer that is dedicated solely to navigation.

As what we know, time-sharing machine is a shared process which different users can access the entire computer in the same time. The more complex it can get the more dangerous and harmful the threats can be on that computer. Unlike in a dedicated machine, one user can only access the file at a time so the lesser will be the harm on the machine.