[Curiosities] Computer

[Mindsphere.]

 

 

A computer, also called a computer system, computer or computer, is a machine that processes data and information according to a list of instructions called a program. Nowadays computers are mostly made of electronic components and that is why the word "computer" usually means an electronic computer. Computers that are freely programmable and can, at least in principle, process any kind of data or information are called universal (general purpose). Today's computers are not only information processing machines, but also devices that facilitate communication between two or more users, for example in the form of numbers, text, images, sound or video or even all at once (multimedia).

The science of processing information with the help of computers is called computer science. The technology required for their use is called Information Technology, abbreviated TI or IT (from the English term Information Technology).

In principle, any computer that has a certain minimum set of functions (in other words, which can emulate a Turing machine) can perform the functions of any other such computer, whether it is a PDA or a supercomputer. This compatibility has led to the use of computers with similar architectures for various activities, from the calculation of the salary of a company's staff to the control of industrial or medical robots (universal computers).

 

The oldest known mechanism that seems to have been able to function as a calculating machine is considered to be the Antikythira mechanism, dating from 87 BC. and apparently used to calculate the motions of the planets. The technology behind this mechanism is unknown.

With the revival of mathematics and science during the European Renaissance, a succession of mechanical computing devices appeared, based on the clock principle, for example the machine invented by Blaise Pascal. The technique of storing and reading data on punched cards appeared in the 19th century. In the same century, Charles Babbage was the first to design a fully programmable calculating machine (1837), but unfortunately his project would not bear fruit, in part because of the technological limitations of the time.

In the first half of the twentieth century, the computing needs of the scientific community were met by analog computers, highly specialized and increasingly sophisticated. The improvement of digital electronics (due to Claude Shannon in the 1930s) led to the abandonment of analog computers in favor of digital (digital), which models problems in numbers (bits) instead of electrical or mechanical signals. It is difficult to say which was the first digital computer; notable achievements were: the Atanasoff-Berry computer, the Z cars of the German Konrad Zuse - for example the Z3 electromechanical computer, which, although very impractical, was probably the first universal computer, then the ENIAC computer with a relatively inflexible architecture that required wiring modifications at each reprogramming, as well as the British secret computer Colossus, built on lamps and electronically programmable.

The ENIAC design team, recognizing its shortcomings, developed another, much more flexible architecture, which became known as von Neumann architecture or "memorized architecture". This is the basis of almost all current computing machines. The first system built on von Neumann architecture was EDSAC.

In the 1960s, lamps (electronic tubes) were replaced by transistors, which were much more efficient, smaller, cheaper and more reliable, which led to the miniaturization and cheapening of computers. Since the 1970s, the adoption of integrated circuits has further lowered the price and size of computers, allowing, among other things, the advent of personal computers today.

 

Although the design and performance of computers have improved dramatically compared to the 1940s, the principles of von Neumann architecture are still the basis of almost all contemporary computing machines. It is named after the famous Austro-Hungarian mathematician John von Neumann.

This architecture describes a computer with four important modules: the arithmetic-logic unit (UAL), the control unit (UC), the central memory and the input / output devices (abbreviated I / E). They are interconnected with a bundle of wires called the bus on which the calculation data and program data (instructions) flow and are driven in the clockwise direction (continuous pulse string).

Conceptually, a computer's memory can be seen as a number of numbered "cells." Each cell receives its own unique number as an address; they can store a small, predetermined amount of information. The information can be either an instruction or data itself. The instructions tell the computer what to do, and the data is the information that needs to be processed according to the instructions. In principle, any cell can store (memorize) both instructions and data. It is also interesting when one or more instructions, already stored in memory, are seen by other instructions as data to be processed / modified and are therefore themselves dynamically modified ("on the go"), as needed.

 

The above principles can be implemented with a variety of technologies - e.g. Babbage's car was made of mechanical components. But the only such technology that has proved sufficiently practical is that of digital (digital) circuits, electronic circuits that can perform operations in Boolean algebra and binary arithmetic. But the first digital "circuits" used electromechanical relays to represent the states "0" (blocked) and "1" (conduction), arranged in logic gates. The relays were quickly replaced by electronic lamps - electronic vacuum tubes, 100% electronic devices, used until then in analog electronics for their amplification properties, but which could also be used as switches (basic elements in the construction of computers) , 1 → 0 or 0 → 1.

By correctly arranging binary logic gates, it is possible to build circuits that perform more complex functions, such as adders. The electronic adder collects two numbers using the same procedure (in computer terms, algorithm) learned by children at school: each corresponding digit is added, and the "transport" is transmitted to the digits on the left. Consequently, by combining several such circuits, a complete UAL and control unit can be obtained. CSIRAC, one of the first computers based on von Neumann architecture and probably the smallest such computer possible, had about 2000 lamps (tubes) - so even for minimal systems a considerable number of components are needed.

 

Electronic lamps were characterized by several severe limitations in their use for the construction of logic gates: they were expensive, unreliable, took up a lot of space and consumed large amounts of current. Although they were incredibly fast compared to electromechanical relays, they also had a relatively limited operating speed. So since the 1960s lamps (electronic tubes) have been replaced with transistors, devices that work similarly, but were much smaller, faster, more reliable, less current consuming and much cheaper.

From the 1960s and 1970s, the transistor was also replaced by the integrated circuit, which contained several transistors, and the corresponding interconnect wires, on a single silicon plate (called a chip). Since the 1970s, UALs combined with control units (CPUs) have been produced as a unit as integrated circuits, called microprocessors, or CPUs (Central Processing Units). Over time, the density of transistors in integrated circuits has increased incredibly, from a few dozen in the 1970s to over 100 million integrated circuit transistors on Intel and AMD processors since 2005.