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The word computer can be defined in many ways and can also take 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 or, very generally, as any tool that helps computation, in which case one's fingers or even a mathematical formula itself can be considered a computer. Here we are of course mostly concerned with electronic digital computers.

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

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

The power of computers is 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).

Typical Computer

Computers we normally talk about in daily 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:

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 }

name year specs (max, approx) comment
abacus -2500 one of the simplest digital counting tools
Antikythera mechanism -125 ~30 gears, largest with 223 teth 1st known analog comp., by Greeks (mechanical)
slide rule 1620 simple tool for multiplication and division
Shickard's calculating clock 1623 17 wheels 1st known calculator, could multiply, add and sub.
Arithmometer 1820 6 digit numebrs 1st commercial calculator (add, sub., mult.)
Difference Engine 1822 8 digit numbers, 24 axles, 96 wheels mech. digital comp. of polynomials, by Babbage
Analytical Engine design 1837 ~16K RAM, 40 digit numbers 1st general purpose comp, not realized, by Babbage
nomogram 1884 graphical/geometrical tools aiding computation
Z3 1941 176B RAM, CPU 10Hz 22bit 2600 relays 1st fully programmable electronic digital computer
ENIAC 1945 ~85B RAM, ~5KHz CPU, 18000 vaccum tubes 1st general purpose computer
PDP 11 1970 4M RAM, CPU 1.25Mhz 16bit legendary mini
Apple II 1977 64K RAM, 1MHz CPU 8bit popular TV-attached home computer by Apple
Atari 800 1979 8K RAM, CPU 1.7MHz 8bit popular TV-attached home computer by Atari
VIC 20 1980 32K RAM, 1MHz CPU 8bit, 20K ROM successful TV-connected home computer by Commodore
IBM PC 1981 256K RAM, CPU 4.7MHz 16bit, BASIC, DOS 1st personal computer as we know it now, modular
Commodore 64 1982 64K RAM, 20K ROM, CPU 1MHz 8bit very popular TV-connected home computer
ZX Spectrum 1982 128K RAM, CPU 3.5MHz 8bit successful UK TV-connected home comp. by Sinclair
NES/Famicom 1983 2K RAM, 2K VRAM, CPU 1.7MHz 8bit, PPU TV-connected Nintendo game console
Macintosh 1984 128K RAM, CPU 7MHz 32bit, floppy, 512x342 very popular personal computer by Apple
Amiga 1985 256K RAM, 256K ROM, CPU 7MHz 16bit, AmigaOS personal compuer by Commodore, ahead of its time
SNES 1990 128K RAM, 64K VRAM, CPU 21MHz 16bit game console, NES successor
PlayStation 1994 2M RAM, 1M VRAM, CPU 33MHz 32bit, CD-ROM popular TV-connected game console by Sony
TI-80 1995 7K RAM, CPU 980KHz, 48x64 1bit screen famous programmable graphing calculator
Deep Blue 1995 30 128MHz CPUs, ~11 GFLOPS 1st computer to defeat world chess champion
Nintendo 64 1996 8M RAM, CPU 93MHz 64bit, 64M ROM cartr. famous TV-connected game console
GameBoy Color 1998 32K RAM, 16K VRAM, CPU 2MHz 8bit, 160x144 handheld gaming console by Ninetendo
GameBoy Advance 2001 ~256K RAM, 96K VRAM, CPU 16MHz 32bit ARM, 240x160 successor to GBC
Xbox 2001 64M RAM, CPU 733MHz Pentium III TV-connected game console by Micro$oft
Nintendo DS 2004 4M RAM, 256K ROM, CPU ARM 67MHz, touchscreen famous handheld game console by Nintendo
iPhone (aka spyphone) 2007 128M RAM, CPU ARM 620MHz, GPU, cam., Wifi, 480x320 1st of the harmful Apple "smartphones"
ThinkPad X200 2008 8G RAM, CPU 2.6GHz, Wifi legendary laptop, great constr., freedom friendly
ThinkPad T400 2008 8G RAM, CPU 2.8GHz, Wifi legendary laptop, great constr., freedom friendly
Raspberry Pi 3 2016 1G RAM, CPU 1.4GHz ARM, Wifi very popular tiny inexpensive SBC
Arduboy 2016 2.5K RAM, CPU 16MHz AVR 8bit, 1b display tiny Arduino open console
Pokitto 2017 36K RAM, 256K ROM, CPU 72MHz ARM indie educational open console
Raspberry Pi 4 2019 8G RAM, CPU 1.5GHz ARM, Wifi tiny inexpensive SBC, usable as desktop
Deep Thought fictional computer from Hitchhiker's Guide ...
HAL 9000 fictional AI computer (2001: A Space Oddysey)
PD computer planned LRS computer
Turing machine important theoretical computer by Alan Turing

TODO: mnt reform 2, pinephone, NeXT, ti-89, quantum?, wii?

All content available under CC0 1.0 (public domain). Send comments and corrections to drummyfish at disroot dot org.