Definition:
The active program is the piece of software (a set of instructions) that the microprocessor is currently executing. It holds control over the CPU’s resources such as registers, memory, and input/output devices.
Context:
Modern computers often run multiple programs at the same time through multitasking. However, the microprocessor can execute instructions from only one program at any given instant. That program is called the active program.
How it works:
The operating system (OS) manages multiple programs by rapidly switching the CPU’s attention between them. This switching is called context switching. Each time the processor switches to a different program, that program becomes the active program until the next switch.
Importance:
The active program determines what the computer is doing right now — running a word processor, playing a game, or processing a background task. The smooth and efficient handling of active programs is critical for system performance and user experience.
Related concepts:
Process: An instance of a program in execution. The active program is essentially the program whose process is currently scheduled to run.
Thread: A smaller unit within a process; the active thread runs instructions within the active program.
Context switching: The process of saving the state of the current active program and loading the state of the next program to run.