Networks systems

MULTI-TASKING/TIME-SHARING OPERATING SYSTEMS Time-sharing operating system enables people located at a different terminal(shell) to use a single computer system at the same time. The processor time (CPU) which is shared among. Multiple users are termed as time sharing. Real Time OS A real time operating system time interval to the process and response to inputs is very small. Examples: Military Software Systems, Space Software Systems are the Real time OS example. NETWORK OPERATING SYSTEM Network Operating System runs on a server. It provides the capability to serve to manage data,user, groups, security, application, and other networking functions. MOBILE OS Mobile operating systems are those OS which are especially designed to power smartphones, tablets, and wearables devices. Some most famous mobile operating systems are Android and iOS, but others include BlackBerry,Web, and watchOs. FUNCTION OF OPERATING SYSTEM Process management:- Process management helps the OS to create and delete processes. It also provides mechanisms for synchronization and communication among processes. Memory management:- Memory management module performs the task of allocation and deallocation of memory space to programs in need of these resources. File management:- It manages all the file-related activities such as organization storage,retrieval, naming, sharing, and protection of files. Device Management: Device management keeps tracks of all devices. This module also responsible for this task is known as the 1/0 controller. It also performs the task of allocation and deallocation of the devices. I/0 System Management: One of the main objects of any OS is to hide the peculiarities of hardware devices from the user. Secondary-Storage Management: Systems have several levels of storage which includes primary storage,secondary storage, and cache storage. Instructions and data must be stored in primary storage or cache so that a running program can reference it. Security:- Security module protects the data and information of a computer system against malware threat and authorized access. Command interpretation: This module is interpreting commands given by the and acting system resources to process those commands. Networking: A distributed system is a group of processors which do not share memory, hardware devices, or a clock. The processors communicate with one another through the network. Job accounting: Keeping track of time & resources used by various jobs and users. Communication management: Coordination and assignment of compilers, interpreters, and another software resource of the various users of the computer systems. FEATURES OF OPERATING SYSTEM Protected and supervisor mode Allows disk access and file systems Device drivers. Networking Security. Program Execution. Memory management Virtual Memory. Multitasking. Handling I/0 operations. Manipulation of the file system. Error Detection and handling. Resource allocation. Information and Resource Protection. ADVANTAGES OF OPERATING SYSTEM Allows you to hide details of hardware by creating an abstraction. Easy to use with a GUI Offers an environment in which a user may execute programs/applications. The operating system must make sure that the computer system is convenient to use. Operating System acts as an intermediary among applications and the hardware components. It provides the computer system resources with an easy to use format. Acts as an intermediary between all hardware's and software of the system. DISADVANTAGES OF OPERATING SYSTEM If any issue occurs in the OS, you may lose all the contents which have been stored in your system. Operating system's software is quite expensive for small size organizations which adds burden on them. Example Windows. It is never entirely secure as a threat can occur at any time. Name Server Name Server also known as DNS server - map the human-readable names to the IP addresses. Print Server - shares & maintains network printers,can join the domain server. A network with a centralized printing service will have a print server. List Server It provides a better way of managing mailing lists. The server can be either open interactive discussion for the people or a one-way list that provides announcements, newsletters or advertising. Fax Server It is one of the best options for organizations that seek minimum incoming and outgoing telephone resources, but require faxing actual documents. Groupware Server It is software designed that enables the users to work together, irrespective of the location, through the Internet and to function together in a virtual atmosphere. Audio/Video Server It provides multimedia capabilities to websites by helping the user to broadcast streaming multimedia content. What is an ALIAS command? ALIAS name can be given to a table or field. This alias name can be referred to in WHERE clause to identify the table or field with some exceptions. Example-SELECT st.StudentID, Ex.Result FROM student st,Exam AS Ex WHERE st.StudentID = Ex. StudentID Here, st refers to the alias name for the student table and Ex refers to the alias name for the exam table. Virtual Servers Virtual server is a separate computer that shares hardware and software resources with other operating systems (OS) to satisfy the customer's demands. A virtual server is cost-effective and provides faster resource control. IRC Server It is an ideal option for those looking for real-time discussion capabilities. Internet Relay Chat comprises different network servers that enable the users to connect to each other through an IRC network. Relational Operators Use relational operators to evaluate conditions. In addition to the less than (<) and greater than (>) operators, the following operators are available:

Which is the correct operator for equality testing? == The else Clause An optional else clause can be specified to execute a block of code when the condition in the if statement evaluates to false.