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This is a list of the fundamental frequencies in hertz (cycles per second) of the keys of a modern 88-key standard or 108-key extended piano in twelve-tone equal temperament, with the 49th key, the fifth A (called A 4), tuned to 440 Hz (referred to as A440). [1] [2] Every octave is made of twelve steps called semitones.
60 Hz: Electromagnetic – standard AC mains power (American AC, Osaka AC), refresh rate of NTSC CRT televisions and standard refresh rate of computer monitors: 10 2: 100 Hz 100 Hz: Cyclic rate of a typical automobile engine at redline (equivalent to 6000 rpm) 261.626 Hz: Acoustic – the musical note middle C (C 4) 440 Hz: Acoustic – concert ...
ISO/IEC 9995 Information technology — Keyboard layouts for text and office systems is an ISO/IEC standard series defining layout principles for computer keyboards. It does not define specific layouts but provides the base for national and industry standards which define such layouts.
The UK variant of the Enhanced keyboard commonly used with personal computers designed for Microsoft Windows differs from the US layout as follows: . The UK keyboard has 1 more key than the U.S. keyboard (UK=62, US=61, on the typewriter keys, 102 v 101 including function and other keys, 105 vs 104 on models with Windows keys)
This variation led in the 18th century to an increase in the use of equal temperament, in which the frequency ratio between each pair of adjacent notes on the keyboard was made equal. In other words, the ratio between two notes that were one octave apart was kept pure, and the twelve notes in between the octave were equally spaced from one ...
Pitch is the number of letters, numbers and spaces in one inch (25.4 mm) of running text, that is, characters per inch (abbreviated cpi), measured horizontally. [1] [2] The pitch was most often used as a measurement of the size of typewriter fonts as well as those of impact printers used with computers.
[a] The ratio of the frequency of one note in the scale to that of the preceding note is given by . [1] In equal temperament, all the semitones have the same size (100 cents), and there are twelve semitones in an octave (1200 cents). As a result, the notes of an equal-tempered chromatic scale are equally-spaced.
1.8×10 1: ENIAC, first programmable electronic digital computer, 1945 [2] 5×10 1: upper end of serialized human perception computation (light bulbs do not flicker to the human observer) 7×10 1: Whirlwind I 1951 vacuum tube computer and IBM 1620 1959 transistorized scientific minicomputer [2]