The System Nucleus

In the last chapter we developed the concepts and tools needed to build the paper operating system outlined in chapter 1. As mentioned there, the paper operating system will resemble an onion in which each layer provides a set of functions dependent only on the layers within it. At the centre of the onion are the facilities provided by the hardware of the machine itself. The onion layers can be regarded as implementing successive virtual machines, so that the onion as a whole implements the virtual machine required by the user.