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