3. (a) What is a microkernel? [6%] (b) Why is an efficient implementation of inter-process communication critical for the efficiency of microkernels? [6%] (c) You are asked to write a device driver in a microkernel system for a digital camera connected to the usb-bus, which contains a tape to store the videos. The device driver has to fulfil two functions. Firstly, it has to access the data which is on the tape in the digital camera on a FAT-filesystem, and secondly it has to control the movements of the tape (move it forward, backwards and stop it). Which parts of the device driver must be implemented in the microkernel, and which parts may be implemented as services in user mode? Justify your answer. [8%]