-USER'S VIEW -OS is designed mostly for ease of users, with some
attention to performance and none to resource utilization.
-SYSTEM'S VIEW- OS serves as resource allocator.
-OS as a control program.
2.Explain the goals of OS.
- Execute user programs and make solving user problems.
- make the computer system convenient to use.
3.What's the difference between Batch systems, multiprogrammed systems, and time-sharing systems?
-Batch system has been associated with mainframe computers since the earliest days of electronic computing in 1950s. Because such computers were enormously costly, batch processing was the only economically-viable option of their use. In those days, interactive sessions with either text-based computer terminal interfaces or graphical user interfaces were not widespread. Initially, computers were not even capable of having multiple programs loaded into the main memory.
- Multiprogrammed systems, process delays are quite common, due to preemptions. Most lock-based synchronization algorithms perform poorly in the face of such delays, because a delayed process holding a lock can impede the progress of other processes waiting for that lock. Furthermore, lock-based algorithms are susceptible to problems such as deadlock and priority inversion. Lock-free and wait-free algorithms are implemented without locking mechanisms, and therefore do not suffer from these problems. This framework will be established through a combination of research on new algorithmic techniques for efficiently implementing lock-free and wait-free shared objects in multiprogrammed systems, and new lower-bound and impossibility results that help reveal characteristics that optimal or near-optimal algorithms must have. The framework to be developed will be evaluated experimentally through research involving simulation models, synthetic workloads, and real-world applications.
-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.
4.Advantages of parallel systems.
Parallel processing advantages os shared memory systems are these:
-memory access is cheaper than inter-code communication. This means that internal synchronization is faster than using the lock manager.
-shared memory system are easier to administer than a cluster.
5.Differentiate Sytemmetric Multiprocessing and Asymmetric Multiprocessing.
-symmetric multiprocessing or SMP involves a multiprocessor computer-architecture where two or more identical processors can connect to a single shared main memory. Most common multiprocessor systems today use an SMP architecture. In the case of multi-core processors, the SMP architecture applies to the cores, treating them as separate processors.
SMP systems allow any processor to work on any task no matter where the data for that task are located in memory; with proper operating system support, SMP systems can easily move tasks between processors to balance the workload efficiently.
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.
6.Differentiate client-server systems and peer-to -peer systems.
Client-server
computing or networking is a distributed application architecture that partitions tasks or work loads between service providers (servers) and service requesters, called clients.[1] Often clients and servers operate over a computer network on separate hardware. A server is a high-performance host that is a registering unit and shares its resources with clients. A client does not share any of its resources, but requests a server's content or service function. Clients therefore initiate communication sessions with servers which await (listen to) incoming requests.
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.
7.Differentiate the design issues of OS between a stand-alone PC and workstation
connected to a network.
a Stand-alone PC- refers to a device that is self-contained, one that does not require any other devices to function. For example, a fax machine is a stand alone device because it does not require a computer, printer, modem or other device. A printer, on the other hand is not a stand- alone device because it requires a computer to feed it data.
a workstation is a high-end microcomputer designed for technical or scientific applications.
intended primarily to be used by one person at a time, they commonly connected to a local
are network and run multi user-operating systems. The term workstation has also been used
to refer to a mainframe computer terminal or a PC connected to a network.
8.Define the essential properties of the following types of OS:
a.Batch- has been associated with mainframe computers since the earliest days of electronic computing in 1950s. Because such computers were enormously costly, batch processing was the only economically-viable option of their use. In those days, interactive sessions with either text-based computer terminal interfaces or graphical user interfaces were not widespread. Initially, computers were not even capable of having multiple programs loaded into the main memory.
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- real-time computing (RTC) is the study of hardware and software systems that are subject to a "real-time constraint"—i.e., operational deadlines from event to system response. By contrast, a non-real-time system is one for which there is no deadline, even if fast response or high performance is desired or preferred. The needs of real-time software are often addressed in the context of real-time operating systems, and synchronous programming languages, which provide frameworks on which to build real-time application software.
A real time system may be one where its application can be considered (within context) to be mission critical. The anti-lock brakes on a car are a simple example of a real-time computing system — the real-time constraint in this system is the short time in which the brakes must be released to prevent the wheel from locking. Real-time computations can be said to have failed if they are not completed before their deadline, where their deadline is relative to an event. A real-time deadline must be met, regardless of system load.
d.Network- A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network.
e.Distributed -Distributed computing deals with hardware and software systems containing more than one processing element or storage element, concurrent processes, or multiple programs, running under a loosely or tightly controlled regime.
In distributed computing a program is split up into parts that run simultaneously on multiple computers communicating over a network. Distributed computing is a form of parallel computing, but parallel computing is most commonly used to describe program parts running simultaneously on multiple processors in the same computer. Both types of processing require dividing a program into parts that can run simultaneously, but distributed programs often must deal with heterogeneous environments, network links of varying latencies, and unpredictable failures in the network or the computers.
f.Handheld-Handheld PC, or H/PC for short, is a term for a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a Palmtop. The first handheld device compatible with desktop IBM personal computers of the time was the Atari Portfolio of 1989. Another early model was the Poqet PC of 1989 and the Hewlett Packard HP 95LX of 1991. Other MS DOS compatible hand-held computers also existed.
Some Handheld PCs run on Microsoft's Windows CE operating system, with the term also covering Windows CE devices released by the broader commercial market.
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