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MCA Articles
Page 72 of 94
Running vs Waiting vs Terminated Process
A process is an active program. It can also be said as a program that is under execution. It is more than the program code as it includes the program counter, process stack, registers, program code etc.A process passes through different states as it executes. A diagram that illustrates all these states is as follows −Details about the running, waiting and terminated process are given as follows −Running ProcessThe process is said to be in running state when the process instructions are being executed by the processor. This is done once the process is assigned to the processor using the ...
Read MoreShort-term vs medium-term vs long-term scheduling
Process Scheduling handles the selection of a process for the processor on the basis of a scheduling algorithm and also the removal of a process from the processor. It is an important part of multiprogramming in operating system.Process scheduling involves short-term scheduling, medium-term scheduling and long-term scheduling. Details about these are given as follows −Long-Term SchedulingLong-term scheduling involves selecting the processes from the storage pool in the secondary memory and loading them into the ready queue in the main memory for execution. This is handled by the long-term scheduler or job scheduler.The long-term scheduler controls the degree of multiprogramming. It ...
Read MoreMajor Activities of an Operating System with Regard to Secondary Storage Management
Secondary storage devices are non-volatile devices where the data is stored for long-term storage. Disks are the mainly used secondary storage devices. They provide the bulk of secondary storage in operating systems today.The main activity that is performed in secondary storage management is disk scheduling. There are many disk scheduling algorithms. However, the important ones are FCFS scheduling, SSTF scheduling, SCAN scheduling and LOOK scheduling.All the disk scheduling algorithms are explained using the following requests for the disk -10, 95, 23, 78, 80First Come First Served SchedulingIn first come first served scheduling, the requests are serviced in their coming order. ...
Read MoreMathematical Logic Statements and Notations
PropositionA proposition is a collection of declarative statements that has either a truth value "true” or a truth value "false". A propositional consists of propositional variables and connectives. We denote the propositional variables by capital letters (A, B, etc). The connectives connect the propositional variables.PredicateA predicate is an expression of one or more variables defined on some specific domain. A predicate with variables can be made a proposition by either assigning a value to the variable or by quantifying the variable.The following are some examples of predicates −Let E(x, y) denote "x = y"Let X(a, b, c) denote "a + ...
Read MoreQOS Traffic Scheduling
QoS traffic scheduling is a scheduling methodology of network traffic based upon QoS (Quality of Service). Here, the frames or packets are mapped to internal forwarding queues based on its QoS information, which are then services according to a queuing scheme.Typically, multiple queues are present each with different priority levels. The scheduler decides the type of treatment to be given to the traffic in each queue. When traffic is available, the scheduler maps it to the appropriate queue. For example, video and voice traffic are kept is queued with higher priority than background traffic.Notable QoS Traffic Scheduling MethodsWeighted Round Robin ...
Read MoreComparison of 802.16 with 802.11
IEEE 802.16 is a standard that defines Wireless Interoperability for Microwave Access (WiMAX), a wireless technology that delivers network services to the last mile of broadband access.The IEEE 802.11 standard that lays down the specifications of the wireless local area networks (WLAN) or Wi-Fi, that connects wireless devices within a limited area.The following chart gives a comparison between 802.16 and 802.11 −FeatureIEEE 802.16IEEE 802.11TechnologyDefines WIMAX.Defines WLANs or WiFi.Application AreaLast-mile of broadband wireless access.Limited area forming wireless LANs.Versions of the Standard802.16a, 802.16d, 802.16e, 802.16m etc.802.11a, 11b, 11g, 11n, 11ac, 11ad etc.Domain of UsageIt is used for a wide area mostly outdoors.It ...
Read MoreWhat is dynamic frequency selection (DFS)?
Dynamic Frequency Selection (DFS) is a technique used in IEEE 802.11 wireless networks or WiFi that permits devices to dynamically switch the operating frequency of transmission in order to avoid interference with other devices.FeaturesDFS is a legal mandate for all IEEE 802.11 devices which share 5 GHz radio spectrum with radar.DFS was adopted in IEEE 802.11h standard for wireless transmissions. It came up in 2003, when the wireless network started using 5 GHz band that is primarily used by radar systems.The objective of DFS is to prevent co-channel interference of signals between the primary user, i.e. radar systems, and the ...
Read MoreWhat is wireless broadband (WiBB)?
Wireless broadband (WiBB) a networking technology designed to impart highspeed Internet and data service through wireless networks. Wireless broadband may be delivered through wireless local area networks (WLANs) or wide area networks (WWANs).Similar to other wireless services, wireless broadband can be either fixed or mobile.Features of WiBBWiBB is similar to wired broadband service since they connect to an internet backbone, with the difference that they use radio waves instead of cables to connect to the last mile of the network.The range of most broadband wireless access (BWA) services varies around 50 km from the transmitting tower.Download speeds provided by some ...
Read MoreAdvanced Encryption Standard (AES)
The Advanced Encryption Standard, or AES, is an encryption standard established in 2001 by the National Institute of Standards and Technology (NIST) of USA. It is implemented worldwide both in hardware and software to encrypt sensitive data. AES finds wide usage while transmitting data over computer networks, particularly in wireless networks.Features of AESAES is a subset of Rijndael block cipher.It is a successor of Data Encryption Standard (DES) and is stronger and faster than DES.It is a symmetric key symmetric block cipher.It operates on 128-bit (16 bytes) data.The cipher key may be of 128, 192 or 256 bits.All computations are ...
Read MoreWired Equivalent Privacy (WEP)
Wired Equivalent Privacy (WEP) is a security standard for wireless networks or WiFi. It was a part of the original IEEE 802.11 protocol. As wireless networks transmit data over radio waves, eavesdropping on wireless data transmissions is relatively easier than in wired networks connected by cables. WEP aims to provide the same level of security and confidentiality in wireless networks as in wired counterparts.Features of WEPWEP was introduced as a part of IEEE 802.11 standard in 1997.It was available for 802.11a and 802.11b devices.WEP uses encryption of data to make it unrecognizable to eavesdroppers.It uses RC4, a stream cipher, for ...
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