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The taskbar allows the user to locate and launch programs through the Start button or view any program that is currently open. It also allows them to check the date and time, items running in the background through the Systray.

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The Multiplexer acts as a multiple-input and single-output switch. Multiplexer is also known as Data Selector. For example A 4-to-1 multiplexer contains four input signals and one output signal.

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Some key differences are:

1. Resource included by include directive is loaded during jsp translation time while resource included by include action is loaded during request time.

2. Any change on included resource will not be visible in case of include directive until jsp file compiles

again. While in case of include action any change in included resource will be visible in next request.

3. include directive is static import while include action is dynamic import

4. include directive uses file attribute to specify resource to be included while include action use page attribute for same purpose.

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The D flip-flop is a modification of the clocked SR flip-flop. The D input goes directly into the S input and the complement of the D input goes to the R input. The D input is sampled during the occurrence of a clock pulse. If it is 1, the flip-flop is switched to the set state (unless it was already set). If it is 0, the flip-flop switches to the clear state.

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Internet

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A file is a collection of records which have common properties. Each file has its own file reference which is unique. The file reference indicates the subject or contexts of the records.

A record can be an image, text based or in electronic or physical format.

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The five services are:

a. Program execution. The operating system loads the contents (or sections) of a file into memory and begins its execution. A userlevel program could not be trusted to properly allocate CPU time.

b. I/O operations. Disks, tapes, serial lines, and other devices must be communicated with at a very low level. The user need only specify the device and the operation to perform on it, while the system converts that request into device- or controller-specific commands. User-level programs cannot be trusted to access only devices they should have access to and to access them only when they are otherwise unused.

c. File-system manipulation. There are many details in file creation, deletion, allocation, and naming that users should not have to perform. Blocks of disk space are used by files and must be tracked. Deleting a file requires removing the name file information and freeing the allocated blocks. Protections must also be checked to assure proper file access. User programs could neither ensure to protection methods nor be trusted to allocate only free blocks and deallocate blocks on file deletion.

d. Communications.Message passing between systems requires messages to be turned into packets of information, sent to the network controller, transmitted across a communications medium, and reassembled by the destination system. Packet ordering and data correction must take place. Again, user programs might not coordinate access to the network device, or they might receive packets destined for other processes.

e. Error detection. Error detection occurs at both the hardware and software levels. At the hardware level, all data transfers must be inspected to ensure that data have not been corrupted in transit. All data on media must be checked to be sure they have not changed since they were written to the media. At the software level, media must be checked for data consistency, for instance, whether the number of allocated and unallocated blocks of storage match the total number on the device. There, errors are frequently processindependent (for instance, the corruption of data on a disk), so there must be a global program (the operating system) that handles all types of errors. Also, by having errors processed by the operating system, processes need not contain code to catch and correct all the errors possible on a system.

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Network topology refers to the physical or logical layout of a network. It defines the way different nodes are placed and interconnected with each other. 

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A structure defined within another structure is known as a nested structure.

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Half Duplex is the system in which either data is transmitted or received (any one process at a time). For eg. walkie-talkie Full duplex is the system in which data is transmitted and received simultaneously. For eg. mobile phone