Q.6)
a.)Explain Process Control Block. Ans. A process is a program in execution. In operating system each process is represented by process control block (PCB). It is also called as task control block. PCB contains the important information about specific process.
Information associated with each process is as follows.
- Process State: The state may be any one of the following new, ready, running,waiting, halted, and so on.
- Program counter: It provides the information about the address of the next instruction to be executed for this process.
- CPU registers: CPU registers include general purpose register, stack pointers, index registers etc. Number of register and its type depends upon the computer architecture.
- Memory Management Information: It contains the information about address of process such as the value of base and limit registers, the page tables, or the segment tables depending on the memory system used by the operating system
- Scheduling Information: This information contains priority of process, if any interrupt occur, then higher priority process will get chance to execute.
b) Explain File Allocation Table.
Operating system maintains all files on the hard disk using a table called as File Allocation Table.Disk creates cluster for file storage. A cluster is the logical unit of file storage on a hard disk.These clusters can be scattered among different locations on the hard disk. Any file stored on a hard disk takes one or more clusters of storage.Clusters those are associated with file have entry in file allocation table. When you want to read a file, operation system search the index in FAT for associated cluster and provides the file for reading.
