A mechanical device for drawing conclusions from typically elaborate premises, for solving complex problems when the
parameters are known, for aggregating (
see aggregation )
data , for the
simulation or
control of a
system. Because the original use of computers as arithmetic has been surpassed by recent technological accomplishments and because all
computation al tasks involve
information, computers are often called information processors (
see computing ). All computers have
input devices, arithmetic units and
output devices. Input devices read data in the form of Hollerith cards, magnetic tapes or disks, or accept signals from remote typewriter-like terminals or from the measuring devices applied at fixed points of a process. Output devices can print or display information on TV screens, prepare industrial drawings, produce data compatible with those read (
see reconstructability ) or generate signals to control a process (
see automation ). The arithmetic unit processes information according to a
program which the computer user must supply or invoke. Whereas early computers were strictly input-output devices, e.g., for computing an algebraic expression, modern computers are capable of
iteration by entering its computational results into its own input, capable of compilation (
see compiler ) by converting a higher order programming language more suitable to the human programmer into the machine language which organizes the arithmetic unit so as to engage in the intended computation, and capable of self-programming by computing a program suitable to computing a particular problem. Finally, the combination of computers and
communication technology has paved the way to peripheral and interactive uses, to the decentralization of computation facilities and to computer
networks linking users and information resources in unprecedented ways. Most computers are sequential machines in the sense that they do one thing at one time and at one place in the arithmetic unit. Networking has opened up the possibility of distributed computation and parallel processing. Here, computation may occur in different facilities simultaneously. At some point in time, their results are merged and then again distributed to other facilities, thus establishing a network of computation very different from sequential processes. Parallel computation is also thought to be underlying computation by the human brain (
see computing, analog COMPUTERS, digital COMPUTERS). (
Krippendorff )
