Network Operating System:
A Network Operating System runs on a server arid provides the server the capability to manage data, users, groups, security, applications, and other networking functions. The primary purpose of the network operating system is to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks.
Examples of network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare and BSD.
The advantages of network operating systems are as follows:
- Centralized servers are highly stable.
- Security is server managed.
- Upgrades to new technologies and hardware can be easily integrated into the system.
- Remote access to servers is possible from different locations and types of systems
The disadvantages of network operating systems are as follows:
- High cost of buying and running a server.
- Dependency on a central location(server) for most operations.
- Regular maintenance and updates are required.
Multi Programming:
Multi Programming Operating System is the name given to the interleaved execution of two or more different and independent programs by the same computer. Interleaving of programs mean chain of programs that are either in running phase, ready or blocked phase. It is an efficient way to improve the system performance.
Multi programming approach permits more than one job to utilize the CPU time at any moment by applying the scheduling techniques like first come first serve, shortest job first etc . The more the number of programs requesting for system resources, resource utilization would be better. The operating system picks up any of the programs as scheduled and starts execution.
An OS does the following activities related to multiprogramming.
- The operating system keeps several jobs in memory at a time.
- This set of jobs is a subset of the jobs kept in the job pool.
- The operating system picks and begins to execute one of the jobs in the memory.
- Multiprogramming operating systems monitor the state of all active programs and system resources using
- memory management programs to ensure that the CPU is never idle, unless there are no jobs to process.
Advantages:
- High and efficient CPU utilization.
- User feels that many programs are allotted CPU almost simultaneously.
Disadvantages:
- CPU scheduling is required.
- To accommodate many jobs in memory, memory management is required.
