less_retarded_wiki

Computer

The word computer may be defined in countless ways and can also adopt many different meanings; a somewhat common definition may be this: computer is a machine that automatically performs mathematical computations. We can also see it as a machine for processing information, manipulating symbols or, very generally, as any tool that helps computation, in which case not just laptops, desktops and cellphones fit the definition, but also primitive computers like a sundial, one's fingers or even a mathematical formula. But nowadays the word of course implicitly implies an electronic digital computer.

The electronic digital computer turned out to be one of the greatest technological inventions in history for numerous reasons -- firstly computers allowed creation of many other things which previously required too complex calculations, such as highly complex planes, space rockets and undreamed of factories (and, of course, yet more powerful computers which is why we've seen the exponential growth in computer power), they also allow us to crunch extreme volumes of data and accelerate science; secondly they offered extremely advanced work tools like robots, virtual 3D visualizations, artificial intelligence and physics simulators, and they also gave us high quality, cheap multimedia and entertainment like games -- with computers anyone can shoot video, record music, carry around hundreds of movies in his pocket or fly a virtual plane. Most important however is probably the fact that computers enabled the Internet -- by this they forever changed the world.

We can divide computers based on many attributes, e.g.:

• by continuous or discrete representation of data: digital vs analog
• by hardware technology: electronic ("lightning in sand"), mechanical, quantum, biological etc.
• by purpose: special purpose vs general purpose, personal, server, calculator, embedded, workstation, supercomputers, gaming computer etc.
• by programmability: non-programmable, partially or fully programmable
• by the theoretical model of computation it is based on: Turing machine, lambda calculus etc.
• by computational power: how difficult problems the computer is able to solve, i.e. where in the Chomsky hierarchy it stands (typically we want Turing complete computers)
• by other criteria: price, reliability, durability etc.

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On the left typical personal computer, with case, monitor, keyboard, mouse and speakers; on the right a pocket mechanical calculator of the Curta type.

Computers are theoretically studied by computer science. The kind of computer we normally talk about consists of two main parts:

• hardware: physical parts
• software: programs executed by the hardware, made by programmers

The power of computers is mathematically limited, Alan Turing mathematically proved that there exist problems that can never be completely solved by any algorithm, i.e. there are problems a computer (including our brain) will never be able to solve (even if solution exists). This is related to the fact that the power of mathematics itself is limited in a similar way (see Godel's theorems). Turing also invented the theoretical model of a computer called the Turing machine. Besides the mentioned theoretical limitation, many solvable problems may take too long to compute, at least with computers we currently know (see computational complexity and P vs NP).

And let's also mention some curious statistics and facts about computers as of the year 2024. The fist computer in modern sense of the word is frequently considered to have been the Analytical Engine designed in 1837 by an Englishman Charles Babbage, a general purpose mechanical computer which he however never constructed. After this the computers such as the Z1 (1938) and Z3 (1941) of a German inventor Konrad Zuse are considered to be the truly first "modern" computers. Shortly after the year 2000 the number of US households that had a computer surpassed 50%. The fastest supercomputer of today is Frontier (Tennessee, USA) which achieved computation speed of 1.102 exaFLOPS (that is over 10^18 floating point operations per second) with power 22.7 MW, using the Linux kernel (like all top 500 supercomputers). Over time transistors have been getting much smaller -- there is the famous Moore's law which states that number of transistors in a chip doubles about every two years. Currently we are able to manufacture transistors as small as a few nanometers and chips have billions of them. { There's some blurriness about exact size, apparently the new "X nanometers" labels are just marketing lies. ~drummyfish }

Typical Computer

Computers we ordinarily talk about in everyday conversations are electronic digital mostly personal computers such as desktops and laptops, possibly also cell phones, tablets etc.

Such a computer consists of some kind of case (chassis), internal hardware plus peripheral devices that serve for input and output -- these are for example a keyboard and mouse (input devices), a monitor (output device) or harddisk (input/output device). The internals of the computer normally include:

• motherboard: The main electronic circuit of the computer into which other components are plugged and which creates the network and interfaces that interconnect them (a chipset). It contains slots for expansion cards as well as connectors for external devices, e.g. USB. In a small memory on the board there is the most basic software (firmware), such as BIOS, to e.g. enable installation of other software. The board also carries the clock generator for synchronization of all hardware, heat sensors etc.
• CPU (central processing unit): Core of the computer, the chip plugged into motherboard that performs general calculations and which runs programs, i.e. software.
• RAM/working memory/main memory: Lower capacity volatile (temporary, erased when powered off) working memory of the computer, plugged into motherboard. It is used as a "pen and paper" by the CPU when performing calculations.
• disk: Non-volatile (persisting when powered off) large capacity memory for storing files and other data, connected to the motherboard via some kind of bus. Different types of disks exist, most commonly hard disks and SSDs.
• expansion cards (GPU, sound card, network card, ...): Additional hardware cards plugged into motherboard for either enabling or accelerating specific functionality (e.g. GPU for graphics etc.).
• PSU (power supply unit): Converts the input electrical power from the plug to the electrical power needed by the computer.
• other things like fans for cooling, batteries in laptops etc.

Notable Computers

Here is a list of notable computers.

{ Some nice list of ancient computers is here: https://xnumber.com/xnumber/frame_malbum.htm. ~drummyfish }

TODO: mnt reform 2, pinephone, 3DO, ti-89, quantum?

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