Computer Architecture

A computer architecture is a detailed specification of the computational, communication, and data storage elements (hardware) of a computer system, how those components interact (machine organization), and how they are controlled (instruction set). A machine’s architecture determines which computations can be performed most efficiently, and which forms of data organization and program design will perform optimally. The term architecture as applied to computer design, was first used in 1964 by Gene Amdahl, G. Anne Blaauw, and Frederick Brooks, Jr., the designers of the IBM System/360. They coined the term to refer to those aspects of the instruction set available to programmers, independent of the hardware on which the instruction set was implemented. The System/360 marked the introduction of families of computers, that is, a range of hardware systems all executing essentially the same basic machine instructions. The System/360 also precipitated a shift from the preoccupation of computer designers with computer arithmetic, which had been the main focus since the early 1950s. In the 1970s and 1980s, computer architects focused increasingly on the instruction set. In the current decade, however, designers’ main challenges have been to implement processors efficiently, to design communicating memory hierarchies, and to integrate multiple processors in a single design. It is instructive to examine how this transition from concentrating on instruction sets to high-level integration has taken place.