ARMs for the poor: Selecting a processor for teaching computer architecture

Teachers of computer architecture and organization courses have to choose a target processor to illustrate the basic principles of instruction set design. In this paper we suggest that it is time to choose the ARM processor architecture that is markedly different to those used in most current courses. A specific computer architecture is required as a vehicle to teach about registers, addressing modes, instruction types, and so on. Resorting to a hypothetical teaching machine reduces the student's learning burden and makes their learning curve shallow, but failing to introduce them to the complexities they will encounter in the real world can destroy their motivation. Teachers are concerned not only with covering a body of knowledge; they must motivate students and create a sense of excitement. In a discipline as rapidly changing as computer science, only those students who can adapt to change are likely to thrive over the four or more decades of their career. This paper explains why the ARM architecture is an excellent vehicle for teaching computer architecture; in particular, its predicated execution, inclusion of shifting in all data-processing instructions, and its compressed code (Thumb) mode. Moreover, the ARM has a RISC architecture with some traditional CISC architectural features.