On large computers, the operating system switches back and forth among multiple programs stored in memory in order to overlap input and output operations with processing time; the purpose of this switching is to maximize the work done by the CPU. What is this concept of switching among multiple programs in memory called?

Multiprogramming

Explanation:

Multiprogramming: 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 effectively and efficiently.

One of the most important aspects of an Operating System is to multi program.

In a computer system, there are multiple processes waiting to be executed, i.e. they are waiting when the CPU will be allocated to them and they begin their execution. These processes are also known as jobs. Now the main memory is too small to accommodate all of these processes or jobs into it. Thus, these processes are initially kept in an area called job pool. This job pool consists of all those processes awaiting allocation of main memory and CPU.

CPU selects one job out of all these waiting jobs, brings it from the job pool to main memory and starts executing it. The processor executes one job until it is interrupted by some external factor or it goes for an I/O task.