ABSTRACT
This chapter introduces the microprocessor and microcontroller to the reader; the structure, the main building blocks, the differences and the capabilities. Computer architecture differs from computer microarchitecture. Some of the general-purpose registers are available for general use by the programmer and some are dedicated to a specific task. The working registers represent the top of the memory hierarchy pyramid. Arithmetic registers are for temporarily holding the operands and results of the arithmetic operations. The address group is used for making the addressing of data more flexible. The name scratchpad was given to these internal general-purpose registers because they are essentially used to store information in a fast memory. Scratchpad registers differ from usual registers by the way in which they are addressed. The stack is one of the specialized register structures that may also be available on the microprocessor chip.
