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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.
1 hertz (Hz) 1 to 1.66 Hz: Approximate frequency of an adult human's resting heart beat: 1 Hz: 60 bpm, common tempo in music 2 Hz: 120 bpm, common tempo in music ~7.83 Hz: Fundamental frequency of the Schumann resonances: 10 1: 10 hertz 10 Hz: Cyclic rate of a typical automobile engine at idle (equivalent to 600 rpm) 12 Hz
In telecommunication, a standard test tone is a pure tone with a standardized level generally used for level alignment of single links and of links in tandem. [1]For standardized test signal levels and frequencies, see MIL-STD-188-100 for United States Department of Defense (DOD) use, and the Code of Federal Regulations Title 47, part 68 for other Government agencies.
In all systems of tuning, every pitch may be derived from its relationship to a chosen fixed pitch, which is usually A440 (440 Hz), the note A above middle C. For a classical piano and musical theory, the middle C is usually labelled as C 4 (as in scientific pitch notation ); However, in the MIDI standard definition this middle C (261.626 Hz ...
The PC 97 standard requires that a computer's BIOS must detect and work with USB HID class keyboards that are designed to be used during the boot process. Some keyboards implement the USB Boot Keyboard profile specified in the USB Device Class Definition for Human Interface Devices (HID) v1.11 and are explicitly configured to use the boot protocol.
A common test for whether the computer has crashed is pressing the "caps lock" key. The keyboard sends the key code to the keyboard driver running in the main computer; if the main computer is operating, it commands the light to turn on. All the other indicator lights work in a similar way.
In just intonation, the frequencies of the scale notes are related to one another by simple numeric ratios, a common example of this being 1 / 1 , 9 / 8 , 5 / 4 , 4 / 3 , 3 / 2 , 5 / 3 , 15 / 8 , 2 / 1 to define the ratios for the seven notes in a C major scale, plus the return to the ...
The first fully mechanical digital computer, the Z1, operated at 1 Hz (cycle per second) clock frequency and the first electromechanical general purpose computer, the Z3, operated at a frequency of about 5–10 Hz. The first electronic general purpose computer, the ENIAC, used a 100 kHz clock in its cycling unit. As each instruction took 20 ...