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Unformatted text preview: ay in executing his/her commands and will normally feel that he/she is the sole user of the system. In this manner, each user is given the impression that he/she has his/her own computer, whereas actually a single computer is shared among many uses. Requirements of Time-sharing Systems Time-sharing systems typically require the following additional hardware and software features: 1. A number of terminals simultaneously connected to the system so that multiple users can simultaneously use the system in interactive mode. 2. A relatively large memory to support multiprogramming. 3. Memory protection mechanism to prevent one job's instructions and data from other jobs in a multiprogramming environment. 4. Job status preservation mechanism to preserve a job's complete status information when the CPU taken away from it and restoring this information back before the CPU is given back to it again. 5. A special CPU scheduling algorithm that allocates a very short period of CPU time one-by-one to each user process in a circular fashion. 6. An alarm clock mechanism to send an interrupt signal to the CPU after every time slice. Advantages of Time-sharing Systems Although time-sharing systems are complex to design, they provide several advantages to their users. The main advantages of time-sharing system are as follows: 1. Reduces CPU idle time. It will be waste of precious CPU time to allow a single user to use a large computer interactively because his/her speed of thinking and typing is much slower than the processing speed of a computer. While a particular user is engaged in thinking or typing his/her input, a time-sharing system can service many other users. In this manner, time-sharing systems help in reducing the CPU idle time to a great extent, increasing the system throughput. 2. Provides advantages of quick response time. The special CPU scheduling algorithm used in time-sharing systems ensures quick response time to all users. This feature allows users to interact with the system more rapidly while worki...
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This document was uploaded on 04/07/2014.

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