3 Background Processing A Background Task example essay topic

H.N. C MULTI-USER OPERATING SYSTEMS REPORT CHARLES.S. SPENCE 1. Terms of Reference: 1.1 David King, Lecture IT department Coatbridge College, has asked for the following report to be compiled on Multi-User operating System. The report should be submitted for the week of 6.4. 2003 in connection with all the information gained during this period, and to make recommendations as appropriate. 2.

PROCEDURE: The information contained within this report was compiled in the following manner. fae Discussion David King, Lecturer IT department Coatbridge College fae Information taken from course notes & lectures. fae Internet resources. 3. FINDINGS: 3.1 Main features of multi user operating system. 3.1. 1 Resource Sharing What resource sharing means is that the operating system must manage all the resources must be managed in such a way that all processes run some of the time and that the get the resources needed to enable them to complete their task. 3.1. 2 Multi-user operating systems are used on large computers. A mainframe computer system has one very powerful processing unit.

And the random access memory, which write to and read from storage devices such as disk drives, input and output devices such as printers and disk drives many users, will all share this processing unit. 3.1. 3 The operating system is the most important item of software on any computer. This is automatically loaded when the system is switched on and runs continually whilst the system is on. This software continually communicates with hardware and software programs such as word processing continually ensuring that operations are running smoothly. 3.2 Multi-tasking Multi-tasking systems support foreground and background processes, tasks. A foreground task is one that the user interacts directly with using the keyboard and screen. 3.2.

1 In a computer system that supports more than one process at once, some mechanism must be used to switch from one task to another. There are two main methods used to perform this switching. Co-operative switching means that a task that is currently running will voluntarily give up the processor at some time, allowing other processes to run. Pre-emptive switching means that a task that is running will be interrupted. Then the processor is given to another waiting process.

The problem with co-operative switching is one process could hang and thus deny execution of other processes. Pre-emptive scheduling is better. It gives more response to all processes and helps prevent machine lockup. 3.2. 3 Background Processing A background task is one that runs in the background, it does not have access to the screen or keyboard.

Background tasks are usually used for printing. Windows NT Workstation and Windows 95/98 assign a higher priority to foreground tasks. 3.4 Types of Multi-user systems 3.4 Multi- processing As the name suggests a multi processor system refers to the situation where two or more CPUs share the same resources and service the same work. With all the processes working concurrently you can safely say that a multi-processing system will provide more computer power than a single user system. When designing a multi-processor system your main objective is to maximize the availability of the CPU and other system resources. 3.4. 1 Time sliced As all multi user systems are what is called time-sharing systems, meaning that the resources of the CPU must be shared among all the users who are logged on at any one time, one of theses systems is known as the time-sliced system, which operates by switching from one process to another on a timed basis.

This is known as time-slicing. The amount of CPU time, that is allocated to a process i.e. Time-Slice. 3.4. 2 Distributed System Most large organizations nowadays have a number of systems that are interconnected by means of a communication network. These systems are known as distributed systems.

Commonly known as (LAN) Local area network, these systems allow a number of processes to be linked together within a building or a small geographical area by means of cabling or microwave / fibre optic links, a system such as this would be more efficient and more powerful than a single system with a single processor due to its on-line information sharing capabilities. 3.4. 3 MIMD Architectures have multiple processors that each executes an independent stream of machine instructions. The processors execute these instructions by using any accessible data rather than being forced to operate upon a single, shared data stream. Although software processes executing on MIMD architectures can be synchronized by passing data among processors through an interconnection network, or by having processors examine data in a shared memory. 3.4.

3 SIMD Computers were the first systems to be implemented with a massive amount of processors, and were among the first systems to provide computational power above the G FLOP range. A machine in which many data items are operated upon simultaneously by the same data manipulations is classified as an SIMD machine. Many supercomputers utilize the SIMD principle of operation. To efficiently process vectors and matrices, they employ vector-processing units in which multiple arithmetic units (e. g., floating-point processors) operate on a large number of data items simultaneously.

3.5 Hardware Components of Multi-User System 3.5. 1 Processor.