DATABASE: WHAT IS DATABASE: WHAT IS RDBMS • Relational data base management system • Used to manage the database • Introduced by codd . What is table ...
Home Multitasking (Time sharing) Multitasking has the same meaning of multiprogramming but in a more general sense, as it refers to having multiple (programs, processes, tasks, threads) running at the same time. This term is used in modern operating systems when multiple tasks share a common processing resource (e.g., CPU and Memory). Multitasking:As the name itself suggests, multi tasking refers to execution of multiple tasks (say processes, programs, threads etc.) at a time. Ex: In the modern operating systems, we are able to play MP3 music, edit documents in Microsoft Word, surf the Google Chrome all simultaneously, this is accomplished by means of multi tasking. Multitasking is a logical extension of multi programming. Multi programming In a modern computing system, there are usually several concurrent application processes which want to execute. Now it is the responsibility of the Operating System to manage all the processes effe
Home (PCB) or Task Control Block (TCB) • As the operating system supports multi-programmin g , it needs to keep track of all the processes • T he process control block (PCB) is used to track the proces s ’s execution status. • Each block of memory contains information about the process state, program counter, stack pointe r , status of opened files, scheduling algorithms, etc. • All these information is required and must be saved when the process is switched from one state to anothe r . • The process table is an array of PCB’s, that means logically contains a PCB for all of the current processes in the system. (PCB) • P rocess table is an array or linked list • The process table is an a rray of PCB’s, that means logically contains a PCB for all of the current proce
Home Buffering Kernels provide many services related to I/O. Several services—scheduling, buffering, caching, spooling, device reservation, and error handling—are provided by the kernel’s I/O subsystem and build on the hardware and device-driver infrastructure. A buffer, of course, is a memory area that stores data being transferred between two devices or between a device and an application. Caching: A cache is a region of fast memory that holds copies of data or cache is a temporary storage area where frequently accessed data can be stored for rapid access. What does Buffer mean? A buffer is a temporary holding area for data while it's waiting to be transferred to another location. It is usually located in the RAM. The concept of the buffer has developed in order to prevent data congestion from an incoming to an outgoing port of transfer. Computers have many different devices that all operate at varying speeds, and a buffer is needed to act as a sort of te
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