Microprocessor 4

The fourth volume deals with the software aspects of this component. The main characteristics of the Instruction Set Architecture (ISA) of a generic component are detailed. We then study the two ways to alter the execution flow with both classic and interrupt function call mechanisms. This volume details how to program a microprocessor in five chapters. The first two chapters demonstrate the three characteristics of ISA (Instruction Set Architecture, cf. § Vl-3.5). which are: instruction encoding, addressing modes and the instruction set of a generic component. Then, additional notions linked to the instruction set and execution are discussed in the third chapter. This primarily involves the notion of illegal, invalid, reserved and trusted instructions, the notion of memory alignment, orthogonality and the symmetry of the instruction set. as well as the notion of pme, re-entrant and relocatable code. Then, the subjects of execution time, memory requirements, execution modes, portability and virtualization will be discussed. Finally, it ends with aspects that are very important in industry, their hardware and software compatibilities, how to measure execution performances and the criteria for choosing a microprocessor or MPU (Microprocessor Unit). The last two chapters study two ways of altering execution flow. These are the concepts of the sub-program and interruption.