This is known as an 'interrupt'. There is an extensive article explaining interrupts in detail here: http://en.wikipedia.org/wiki/Interrupt
CSU/DSU hardware device (Channel Service Unit/Data Service Unit)
The meaning of processing device is a kind of computer hardware that converts inputs into outputs. An example of a processing device is the CPU.
When the microprocessor receives an Interrupt Service Request (ISR) on the interrupt line it must determine which of the devices connected to that input sent the request.Software Polling is one method by which it can do so.In Software Polling:A software routine is used to identify the device requesting service. It does so by checking each device to see if it was the one needing service.
none, its hard to byte a hardware device
No. A CPU is hardware.
hardware
Yes, a printer is a hardware device, or even better, an output peripheral device.
Every hardware device requires a software program that provides an interface between the operating system and the hardware itself. These programs are known as the hardware device drivers.
A scanner is both hardware and software, the device itself is hardware (all devices are hardware) but the driver(a program) that runs it is software.
a hardware device that is used to send notefication is fsb .
The USB device is hardware.
A stylus is a hardware input device.