Multiprogramming Environment
Programs in a multiprogrammed environment appear to run at the same time. Processes running in a multiprogrammed environment are called concurrent processes. In actuality, the CPU processes one instruction at a time, but can execute instructions from any active process.
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.
If the machine has the capability of causing an interrupt after a specified time interval, then the operating system will execute each program for a given length of time, regain control, and then execute another program for a given length of time, and so on. In the absence of this mechanism, the operating system has no choice but to begin to execute a program with the expectation, but not the certainty, that the program will eventually return control to the operating system.
Time-Sharing Environment
Time-sharing is sharing 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.
A method of computer operation that allows several interactive terminals to use one computer. Although the terminals are actually served in sequence, the high speed of the computer makes it appear as if all terminals were being served simultaneously.
Time-sharing, in computer systems, is an operating system featured with allowing several users to run several tasks(multitasking) concurrently on one processor, or in parallel on many processors.
The main two problems in multiprogramming environment when processes are run concurrently and share the resources are Problems Stealing or copying a user's files; Writing over another program's (belonging to another user or to the OS) area in memory; Using system resources (CPU, disk space) without proper accounting; Causing the printer to mix output by sending data while some other user's file is printing.
Individuals possibly will not steer clear of plagiarism another user’s data but the predicament in that state of affairs is that there is epoch that the collective file is gained, often by deceitful resources, by those who should not have right of entry to them. a further fixation is that, one consumer may use the possessions or the artificial data but lay the blame on expenses to other users.
Another main problem of the Multiprogramming and Time-Sharing Environment is the Using System Resources without proper accounting. System Resource take a big part of the Computer because System Resource is a tool used by either hardware to alert software of a need or by software to control a function of hardware. As what have mention above not proper usage of the system resource can “Cause the printer to mix output by sending data while some other user's file is printing.”
To the conclusion it is so hard for us to secure the security of the multiprogramming and time-sharing for the reason that it allows multiple and numerous users to bring into play the systems. If only possibly will the user may encompass the inadequacy to manipulate the statistics.
