Thursday, June 18, 2009
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-Interleave the execution of the number of processes to maximize processor utilization while providing reasonable response time To be able to load applications, provide for multitasking either through timeslice or priority/interrupt mechanisms, you want to be able to detect a deadlock/race condition and take an appropriate action to resolve the issue, you want to have interprocess communication of some kind, you want to provide communication services for different types of hardware and logical communication consructs, you want to provide "virtual memory" for applications that are larger than physical memory, you want to be able to send a "signal" to process that are waiting for events such as serial I/O and you want to provide user security so that users can have a workspace that cannot be "hacked". Above all, you need to provide access limitations so that viruses cannot gain control. Read about UNIX/Linux. In my opinion it's about as close to a perfect OS as can be found.
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Batch Processing: In batch processing Operating systems the tasks are performed in batches os waits for a batch of tasks to arrive and performs the operation on the batch.
Time Sharing: in time sharing operating systems the operating systems shares the time between the tasks i.e. if job A takes 6 minutes to complete and the predefined time to the os is 2 min it first performs the first job A for 2 minutes then takes up job B(the next one) and this way shares its time between all the jobs arriving. Multi programming: In multiprogramming batch operating systems the multiple jobs are performed by the operating system simultaneously at a time.
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Symmetric Multiprocessing- A multiprocessing architecture in which multiple CPUs, residing in one cabinet, share the same memory. SMP systems provide scalability. As business increases, additional CPUs can be added to absorb the increased transaction volume. SMP systems range from two to as many as 32 or more processors. However, if one CPU fails, the entire SMP system is down. Clusters of two or more SMP systems can be used to provide high availability (fault resilience). If one SMP system fails, the others continue to operate.
Asymmetric multiprocessing or ASMP is a type of multiprocessing supported in DEC's VMS V.3 as well as a number of older systems including TOPS-10 and OS-360. It varies greatly from the standard processing model that we see in personal computers today. Due to the complexity and unique nature of this architecture, it was not adopted by many vendors or programmers during its brief stint between 1970 - 1980.Where as a symmetric multiprocessor or SMP treats all of the processing elements in the system identically, an ASMP system assigns certain tasks only to certain processors. In particular, only one processor may be responsible for fielding all of the interrupts in the system or perhaps even performing all of the I/O in the system. This makes the design of the I/O system much simpler, although it tends to limit the ultimate performance of the system. Graphics cards, physics cards and cryptographic accelerators which are subordinate to a CPU in modern computers can be considered a form of asymmetric multiprocessing.[citation needed] SMP is extremely common in the modern computing world, when people refer to "multi core" or "multi processing" they are most commonly referring to SMP
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A. batch- file that contains a sequence, or batch, of commands. Batch files are useful for storing sets of commands that are always executed together because you can simply enter the name of the batch file instead of entering each command individually. In DOS systems, batch files end with a.BAT extension. For example, the following DOS batch file prints the date and time and sets the prompt to GO>:datetimePrompt [GO>] Whenever you boot a DOS -based computer, the system automatically executes the batch file named AUTOEXEC.BAT, if it exists. Many operating systems use the terms command file or shell script in place of batch file.
B. Time sharing- is sharing a computing resource among many users by multitasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major historical shift in the history of computing. By allowing a large number of users to interact simultaneously on a single computer, time-sharing dramatically lowered the cost of providing computing, while at the same time making the computing experience much more interactive.
C. Real time -It is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based of their priorities while time-sharing operating systems switch tasks based on clock interrupts.
D. Network- a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks. The most common topology or general configurations of networks include the bus, star, Token Ring, and mesh topologies. Networks can also be characterized in terms of spatial distance as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs). A given network can also be characterized by the type of data transmission technology in use on it (for example, a TCP/IP or Systems Network Architecture network); by whether it carries voice, data, or both kinds of signals; by who can use the network (public or private); by the usual nature of its connections (dial-up or switched, dedicated or nonswitched, or virtual connections); and by the types of physical links (for example, optical fiber, coaxial cable, and Unshielded Twisted Pair). Large telephone networks and networks using their infrastructure (such as the Internet) have sharing and exchange arrangements with other companies so that larger networks are created.
E. Distributed-An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each other, gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.
F. Handheld- A handheld computer is a computer that can conveniently be stored in a pocket (of sufficient size) and used while you're holding it. Today's handheld computers, which are also called personal digital assistants (PDAs), can be divided into those that accept handwriting as input and those with small keyboards. The original handheld that accepted handwriting was Apple's Newton, which was later withdrawn from the market. Today, the most popular handheld that accepts handwritten input is the PalmPilot from 3Com. Philips, Casio, NEC, Compaq, and other companies make handhelds with small keyboards. Windows CE and EPOC are two of the most widely used operating systems in handheld computers. Handheld computers are typically used for personal information manager (PIM) types of applications: maintaining schedules, keeping names and phone numbers, doing simple calculations, taking notes, and, with a modem, exchanging e-mail and getting information from the Web. Keyboards have tiny keys that take getting used to. Those that handle handwriting also impose constraints and require some learning. Nevertheless, this class of computer is widely sold and appreciated by many users. Hewlett-Packard has recently
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In terms of disproportionality, Parallel systems usually give results which fall somewhere between pure plurality/majority and pure PR systems. One advantage is that, when there are enough PR seats, small minority parties which have been unsuccessful in the plurality/majority elections can still be rewarded for their votes by winning seats in the proportional allocation. In addition, a Parallel system should, in theory, fragment the party system less than a pure PR electoral system.
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Client-server -computing (often abbreviated to client/server), applications store data on a network server (sometimes called the 'back-end'), but execute the business logic on a client device (the 'front-end'). This two-tier model is primarily associated with Windows computing, since it gained popularity as a result of the emergence of desktop PCs and workstations, along with high-speed local area networking (LAN) technologies. Because of the resource overhead of installing the entire application logic on every single client, clent/server is being superseded by multi-tiered models that take advantage of Internet technologies to distribute application logic more efficiently across the network.
Peer-to-peer (P2P) networking is a method of delivering computer network services in which the participants share a portion of their own resources, such as processing power, disk storage, network bandwidth, printing facilities. Such resources are provided directly to other participants without intermediary network hosts or servers.[1] Peer-to-peer network participants are providers and consumers of network services simultaneously, which contrasts with other service models, such as traditional client-server computing.
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