The Operating System talks to the devices in a computer system using device drivers that are special programs designed to interact with the physical devices of the system.  The device manager isolates the device drivers from the Kernel of the OS and the user applications from the system’s hardware.  It acts as an interface between the device drivers and both the kernel and user applications.  The salient concepts and related terminologies are discussed in the section that follows.

Interrupt

An interrupt is a signal that informs the processor that a particular device wants its attention.  The processor responds to the request, saves the status of the current activity, executes the requested activity and on completion, retrieves the saved activity and resumes the same.  Interrupts are of two types, Hardware Interrupts and Software Interrupts.

System Call

A System call is invoked by a software interrupt that transfers the control to the Kernel.  A System call is executed by a Kernel and uses a CPU instruction to execute more privileged code.

Interrupt Vector

This is an area of memory that contains an array of the addresses of the interrupt service routines that correspond to a specific interrupt number.