Computer Science An Overview _J. Glenn Brookshear _11th Edition
We have already encountered the concept of a pointer in our study of CPUs in Chapter 2. There we found that a register called a program counter is used to hold the address of the next instruction to be executed. Thus, the program counter plays the role of a pointer. In fact, another name for a program counter is instruction pointer.
A CPU consists of three parts (Figure 2.1): the arithmetic/logic unit, which contains the circuitry that performs operations on data (such as addition and subtraction); the control unit, which contains the circuitry for coordinating the machine’s activities; and the
register unit, which contains data storage cells (similar to main memory cells), called registers, that are used for temporary storage of information within the CPU. Some of the registers within the register unit are considered general-purpose registers whereas others are special-purpose registers.