Operating Systems

Abstract

Although programs written for embedded platforms, for example, are often said to execute on “bare metal” (i.e., the unmanaged processor), more usually we write programs that do not execute in isolation or without assistance. More often, they execute on a managed platform which is supported by an Operating System (OS). The OS is a software layer tasked with management of the computer as a whole: it ensures that resources are shared between many executing processes, and performs certain low-level tasks on their behalf. In this chapter the aim is to focus on aspects of OS design and implementation which most directly relate to the hardware and software components the OS manages. We concentrate on UNIX-style concepts and approaches, particularly those which can be supported by SPIM, but the discussion is more generally applicable.