ABSTRACT
This chapter introduces many processors: IBM mainframe, Power personal computers, Alpha, Itanium, and the reduced software solution computer. Issues include reliability, speed, system overhead, and cost. It discusses complex instruction set computer (CISC), reduced instruction set computer (RISC), and virtual machine (VM). Software based VM can be implemented on any superscalar machine. Generally speaking, a RISC machine uses less logic in a pipe that has an execution rate of one stage per clock. As technology advances, a CISC machine can be designed as a decoupled pipe and its stage can also execute in one clock. The virtual address extension (VAX) machine of the 1980s was a fast CISC machine with 304 instructions and 21 addressing modes. The idea was the more, the better. However, the complexity of a VAX processor triggered a revolution in computer design as the concept changed to less is more. The Itanium processor represents a family of chips.
