Computing Through the Ages

A Brief History of Computers

A computer is a machine that can be programmed to perform arithmetic or logical operations automatically.
Modern digital electronic computers can perform generic sets of operations known as programs.
A computer system includes the hardware, operating system, and peripheral equipment needed and used for full operation.
Computers are used in a broad range of industrial and consumer products, including control systems, industrial robots, and personal computers.
Early computers were meant to be used only for calculations, and simple manual instruments like the abacus aided people in doing calculations since ancient times.
The first digital electronic calculating machines were developed during World War II, followed by the microprocessor and the microcomputer revolution in the 1970s.
A modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, along with some type of computer memory, typically semiconductor memory chips.
The first mechanical computer was invented by Charles Babbage in the early 19th century; it was a general-purpose computer that could be described in modern terms as Turing-complete.
During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers.
Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation.
Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog.
The first all-electronic computer was the Atanasoff–Berry Computer (ABC) developed and tested in 1942.A Brief History of Computing Hardware and Technology
Colossus, the world's first electronic digital programmable computer, was delivered in 1944 and used vacuum tubes. It was not Turing-complete.
ENIAC, built in the U.S., was the first electronic programmable computer. Its "program" was defined by patch cables and switches.
Turing proposed the principle of the stored program in his 1936 paper, allowing instructions to be stored in memory.
The Manchester Baby, the first stored-program computer, was operational in 1948 and the prototype for the Ferranti Mark 1, the first commercially available general-purpose computer.
Transistors, invented in 1947, replaced vacuum tubes in the "second generation" of computers and were much more reliable and compact.
The MOSFET, invented in 1959, enabled the practical use of MOS transistors as memory cell storage elements and led to the microcomputer revolution.
The integrated circuit (IC) was first conceived in 1952 and invented by Jack Kilby and Robert Noyce. The MOS IC became the most critical device component in modern ICs, leading to the invention of the microprocessor.
System on a Chip (SoCs) are complete computers on a microchip the size of a coin and are powered by billions of transistors.
Mobile computers, such as laptops and smartphones, run on SoCs and are the dominant computing device on the market.
Computers can be classified by architecture, size/form-factor/purpose, and hardware components.
Hardware components include circuits, computer chips, memory, displays, input/output devices, and power supplies.
A general-purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input/output devices (I/O).Overview of Computer Architecture and Functioning
A computer's central processing unit (CPU) consists of a control unit, arithmetic logic unit (ALU), and registers.
The ALU can perform arithmetic and logic operations, and can compare numbers and return Boolean truth values.
A computer's memory is a list of cells, each with a numbered address that can store a single number.
Each memory cell typically stores binary numbers in groups of eight bits (a byte).
Modern computers have billions or trillions of bytes of memory, including registers used for frequently needed data items.
Input/output (I/O) is how a computer exchanges information with the outside world, including peripherals such as keyboards, displays, and printers.
Multitasking allows a computer to give the appearance of running several programs simultaneously through rapid switching and interrupts.
Multiprocessing distributes a computer's work across several CPUs, and is increasingly available in personal and laptop computers.
Supercomputers have unique architectures and are used for specialized tasks such as large-scale simulation and cryptography.
Software refers to computer programs, libraries, and related data.
Programs are written in programming languages, which can be low-level (specific to a particular CPU architecture) or high-level (more abstract and easier to read).
The stored program architecture is the fundamental concept of storing programs in a computer's memory alongside the data they operate on.Overview of Computers and Computing
Assembly language was used extensively in early computers, but high-level programming languages are now more commonly used to reduce errors and improve convenience for programmers.
Program design for small programs involves analyzing the problem, collecting inputs, using programming constructs, and providing data for output devices.
Large programs require more complex features such as subprograms, modules, formal documentation, and new paradigms like object-oriented programming.
Bugs in computer programs can cause the program or system to fail or crash and are the result of programmer error or an oversight in program design.
The ARPANET, funded by ARPA (now DARPA), was the first computer network that led to the development of the Internet.
Computer networking involves redefining the nature and boundaries of the computer, allowing access to resources of other computers on the network.
Wireless networking, utilizing mobile phone networks, has made networking ubiquitous even in mobile computing environments.
Computers do not need to be electronic and can be made out of many new types of technology, such as optical, DNA, neural, and quantum computers.
Quantum computers hold the most promise for revolutionizing computing and can potentially break some modern encryption algorithms.
Different designs of computers can give very different performance for particular problems.
Artificial intelligence and machine learning are emerging fields that allow computers to learn and adapt.
The use of computers has spawned the need for many standards organizations, clubs, and societies.