Computer hardware

Computer hardware is the collection of physical elements that constitute a computer system. Computer hardware refers to the physical parts or components of a computer such as monitor, keyboard, Computer data storage, hard drive disk, mouse, system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that you can actually touch. In contrast, software is untouchable. Software exists as ideas, application, concepts, and symbols, but it has no substance. A combination of hardware and software forms a usable computing system.
In computer science and engineering, computer architecture is a set of disciplines that describes a computer system by specifying its parts and their relations. Computer architecture is different than the architecture of buildings, the latter is a form of visual arts while the former is part of computer sciences. In both instances (building and computer), a complete design has many details, and some details are implied by common practice.
For example, at a high level, computer architecture may be concerned with how the central processing unit (CPU) acts and how it uses computer memory. Some fashionable (2011) computer architectures include cluster computing and Non-Uniform Memory Access.
Computer architects use computers to design new computers. Emulation software can run programs written in a proposed instruction set. While the design is very easy to change at this stage, compiler designers often collaborate with the architects, suggesting improvements in the instruction set. Modern emulators may measure time in clock cycles: estimate energy consumption in joules, and give realistic estimates of code size in bytes. These affect the convenience of the user, the life of a battery, and the size and expense of the computer's largest physical part: its memory. That is, they help to estimate the value of a computer design.

The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace, describing the analytical engine. Another early example was John Von Neumann's 1945 paper, First Draft of a Report on the EDVAC, which described an organization of logical elements. IBM used this to develop the IBM 701, the company's first commercial stored program computer, delivered in early 1952.
The term “architecture” in computer literature can be traced to the work of Lyle R. Johnson, Mohammad Usman Khan and Frederick P. Brooks, Jr., members in 1959 of the Machine Organization department in IBM’s main research center. Johnson had the opportunity to write a proprietary research communication about the Stretch, an IBM-developed supercomputer for Los Alamos Scientific Laboratory. To describe the level of detail for discussing the luxuriously embellished computer, he noted that his description of formats, instruction types, hardware parameters, and speed enhancements were at the level of “system architecture” – a term that seemed more useful than “machine organization.”
Subsequently, Brooks, a Stretch designer, started Chapter 2 of a book (Planning a Computer System: Project Stretch, ed. W. Buchholz, 1962) by writing, “Computer architecture, like other architecture, is the art of determining the needs of the user of a structure and then designing to meet those needs as effectively as possible within economic and technological constraints.”
Brooks went on to help develop the IBM System/360 (now called the IBM zSeries) line of computers, in which “architecture” became a noun defining “what the user needs to know”. Later, computer users came to use the term in many less-explicit ways.