Wednesday, November 21, 2007

Assignment 1

1. Operating systemFrom Wikipedia, the free encyclopediaJump to: navigation, searchAn operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system. At the foundation of all system software, an operating system performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking and managing file systems. Most operating systems come with an application that provides a user interface for managing the operating system, such as a command line interpreter or graphical user interface. The operating system forms a platform for other system software and for application software.
The operating system (OS) can be considered as the most important program that runs on a computer. Everygeneral-purpose computer must have an operating system to provide a software platform on top of which otherprograms (the application software) can run. It is also the main control program of a computer that schedulestasks, manages storage, and handles communication with peripherals. The central module of an operatingsystem is the 'kernel'. It is the part of the operating system that loads first, and it remains in main memory.Because it stays in memory, it is important for the kernel to be as small as possible while still providing all theessential services required by other parts of the operating system and applications. Typically, the kernel isresponsible for memory management, process and task management, and disk management.In general an application software must be written to run on top of a particular operating system. Your choice ofoperating system, therefore, determines to a great extent the applications you can run. For PCs, the mostpopular operating systems are Windows 95/98, MS-DOS (Microsoft-Disk Operating System), OS/2, but othersare available, such as Linux, BeOS…For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop: itmakes sure that different programs and users running at the same time do not interfere with each other. Theoperating system is also responsible for security, ensuring that unauthorized users do not access the system.From this point of view, operating systems can be classified as follows:§ Multi-user: Allows two or more users to run programs at the same time. Some operating systems permithundreds or even thousands of concurrent users.§ Multiprocessing: Supports running a program on more than one CPU.§ Multitasking: Allows more than one program to run concurrently.§ Multithreading: Allows different parts of a single program to run concurrently.§ Real-time: Real time operating system (RTOS) responds to input instantly. General-purpose operatingsystems, such as DOS and UNIX, are not real-time.An OS is a 16-bit operating system if it processes 16 bits of data at once, e.g.: DOS. On the other hand,Windows 98 and OS/2 Warp are 32-bit operating systems because they can process 32 bits of data at once.A network operating system (NOS) is an operating system which makes it possible for computers to be on anetwork, and manages the different aspects of the network. Some examples are Windows for Workgroups,Windows NT, AppleTalk, DECnet, and LANtastic…
2. The two reasons why regional bank might decide to buy six server computers than 1 super computer: because it makes the work more faster and easier. It performs much better than 1 server.

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