Computer hardware

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For other uses, see Hardware.

PDP-11 CPU board.

Computer hardware (usually simply called hardware when a computing context is concerned) is the collection of physical elements that constitutes a computer system. Computer hardware is the physical parts or components of a computer, such as the monitor, mouse, keyboard, computer data storage, hard disk drive (HDD), graphic cards, sound cards, memory, motherboard, and so on, all of which are physical objects that are tangible.^[1] In contrast, software is instructions that can be stored and run by hardware.

Software is any set of machine-readable instructions that directs a computer's processor to perform specific operations. A combination of hardware and software forms a usable computing system.^[2]

computer system unit

Definition

A typical desktop computer consists of a computer system unit, a keyboard, a mouse, and a monitor. The computer system unit is the enclosure for all the other main interior components of a computer. It is also called the computer case, computer chassis, or computer tower. Cases are typically made of steel or aluminum, but plastic can also be used. While most computer cases are rather dull, black, metal boxes, some manufacturers try to give the unit some flair with color and special design elements.

Computer system unit

Functions

The primary function of the computer system unit is to hold all the other components together and protect the sensitive electronic parts from the outside elements. A typical computer case is also large enough to allow for upgrades, such as adding a second hard drive or a higher-quality video card. It is relatively easy to open up a computer system unit to replace parts and install upgrades. In contrast, it is quite difficult to open up a laptop computer, which is not designed with replacements and upgrades in mind.

In most computer system units, the front side contains the elements a user needs frequently, such as the power button, an optical disk drive, an audio outlet for a pair of headphones, and a number of USB connections. The back side contains all other connections - for power, monitor, keyboard, mouse, Internet connection, and any other peripheral devices. There are typically more connections than the minimum necessary to allow for expansion.

Front (left) and back (right) of a computer system unit.

Inside the Computer Case

Once you open up a computer case, it can initially be difficult to recognize the various components, especially all the different wires. However, if you look closely, you will probably start to recognize a number of components.

Major components inside a computer case

In this particular example, the motherboard is placed vertically, which is quite common. One side of the motherboard is accessible from the back of the computer case - this includes the various connectorsfor input and output devices as well as expansion slots for additional peripherals. The motherboard also contains the central processing unit (CPU), although it can be difficult to see. A large fan is often placed on top of the CPU to avoid overheating. The motherboard also contains the main memory of the computer.

history of computer

The history of computer science began long before the modern discipline of computer science that emerged in the 20th century, and was hinted at in the centuries prior.^{[dubious – discuss][citation needed]} The progression, from mechanical inventions and mathematical theories towards modern computer concepts and machines, led to a major academic field and the basis of a massive worldwide industry.^[1]

The earliest known tool for use in computation was the abacus, developed in the period between 2700–2300 BCE inSumer.^{[citation needed]} The Sumerians' abacus consisted of a table of successive columns which delimited the successive orders of magnitude of their sexagesimal number system.^[2]:11 Its original style of usage was by lines drawn in sand with pebbles .^{[citation needed]} Abaci of a more modern design are still used as calculation tools today.^[3]

The Antikythera mechanism is believed to be the earliest known mechanical analog computer.^[4] It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to c. 100 BCE. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.^[5]

When John Napier discovered logarithms for computational purposes in the early 17th century,^{[citation needed]} there followed a period of considerable progress by inventors and scientists in making calculating tools. In 1623 Wilhelm Schickard designed a calculating machine, but abandoned the project, when the prototype he had started building was destroyed by a fire in 1624 .^{[citation needed]} Around 1640, Blaise Pascal, a leading French mathematician, constructed a mechanical adding device based on a design described by Greek mathematician Hero of Alexandria.^[6] Then in 1672Gottfried Wilhelm Leibnitz invented the Stepped Reckoner which he completed in 1694.^[7]

In 1837 Charles Babbage first described his Analytical Engine which is accepted as the first design for a modern computer. The analytical engine had expandable memory, an arithmetic unit, and logic processing capabilities able to interpret a programming language with loops and conditional branching. Although never built, the design has been studied extensively and is understood to beTuring equivalent. The analytical engine would have had a memory capacity of less than 1 kilobyte of memory and a clock speed of less than 10 Hertz .^{[citation needed]}

Considerable advancement in mathematics and electronics theory was required before the first modern computers could be designed.