Module 1 Topic 2 - Module 1, Topic 2 page 1/7 Module 1,...

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Unformatted text preview: Module 1, Topic 2 page 1/7 Module 1, Topic 2 - Operating Systems. Return to List of Topics. Topics. • Reading • Types of Operation • Types of Operating Systems (OS) o DOS or MSDOS o Windows o OS / 2 o Windows NT o UNIX o Netware o Macintosh System Software • Self Assessment Exercises Reading • Chapter 2 of Systems Administration. • Chapter 4 of Systems Administration. Types of Operation 1. Single tasking Single tasking computers are only capable of performing one job at a time. Traditionally this type of operation was used with early computers which had limited power and speed. The trend towards more sophisticated systems had to wait for cheaper memory, as well as greater power and speed. When these became available, and computers clearly had unused capability, then the development of multi - user and multi - tasking OS's became desirable. However, note that a computer with a single CPU (however powerful), is only capable of performing one task at a time, but it appears to be performing many tasks simultaneously by sharing its processing amongst all the concurrent tasks. Multi - tasking Module 1, Topic 2 page 2/7 This is where several tasks appear to be running at the same time. This is achieved by the Operating System polling around the concurrent jobs and allotting a fair slice of its time to each. Although several tasks may be sharing the CPU, only one of the tasks is actually being processed at any one moment, and the others are suspended but still active. If the system is to be efficient, these suspended jobs must still be resident in RAM so that time is not wasted swapping them back and forth to disk. Thus multi-tasking computers requires fast processor and much memory Windows environments are typical multi - tasking systems. True multi - tasking is where several jobs can run simultaneously, most multi-tasking OS's run one job at a time, using an algorithm to make sure that all jobs have appropriate access to the CPU. True multi-tasking requires several CPU's running in parallel with an operating system that shares simultaneous jobs amongst the CPU's. See the topic on Windows NT for a discussion on SMP (Symmetric Multi Tasking). Single user In this case, the processor is dealing with a single user, that is, there is only one means of access to the CPU. A typical PC is a single user computer, but if some other means of submitting jobs to the CPU was also available, through a modem for instance, then the computer is no longer a single user unit because more than one user can submit jobs at the same time. Note that single user computers may be multi - tasking, windows environments being a typical example. Multi - user In the case of single user computers, there is a great deal of time when the computer's CPU is waiting for a response from the user - a key press for example. This idle time can be available to other users by adding more keyboards and screens to the computer. The operating system must now cope with several users in a similar way to that in which it...
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This note was uploaded on 01/13/2012 for the course ITC 333 taught by Professor Krishnam during the Three '11 term at Charles Sturt University.

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Module 1 Topic 2 - Module 1, Topic 2 page 1/7 Module 1,...

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