digital-to-analog or D/A conversion, the process of changing discrete digital data into a continuously varying signal in relation to a standard or reference. There are two types of converters: electromechanical—also called shaft- or position-to-digital—and electronic. An example of electromechanical conversion is a positioning mechanism, such as a strip-chart recorder. The most common use of an electronic converter is to present the output of a digital computer as a graphic display (see computer graphics) or as audio output, as in computer-generated music. A modem, or data set, is a device that converts the digital signals produced by computers and terminals into analog signals that telephone circuits are designed to carry and then back to digital signals at the other end of the communication link. See also analog-to-digital conversion.

conversion, in psychology: see defense mechanism; hysteria.

analog-to-digital or A/D conversion, the process of changing continuously varying data, such as voltage, current, or shaft rotation, into discrete digital quantities that represent the magnitude of the data compared to a standard or reference at the moment the conversion is made. There are two types of converters: electromechanical—also called shaft- or position-to-digital—and electronic. The most common use is to change analog signals into a form that can be manipulated by a digital computer, as in data communications; a modem, or data set, is a device that converts the digital signals produced by computers and terminals into analog signals that telephone circuits are designed to carry and then back to digital signals at the other end of the communication link. Similarly, in digital sound recording, audio signals are transformed into digital data, which are then recorded on a magnetic or optical disk or tape; the digitized data on the recording medium then must be changed back into the analog sound signals that can be used by a stereophonic sound system. See also digital-to-analog conversion.

formerly hysteria

In psychology, a neurosis marked by extreme emotional excitability and disturbances of psychic, sensory, vasomotor, and visceral functions. The earlier concept of hysteria was used frequently in the first half of the 20th century to explain a wide variety of symptoms and behaviours observed particularly in women. (The term hysteria derives from the Greek word for womb, reflecting the Greeks' belief that the condition resulted from disturbances of the uterus.) Disorders with symptoms similar to those of conversion disorder include factitious disorder, dissociative identity disorder, and personality disorder (histrionic type).

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