Reference STATE OF THE ART Stan Augarten

ISBN 0-89919-195-9

Photo of
The Most Widely Used Digital-to-Analog Converter
The DAC-08


Not all electronic machines speak the same language. Some use binary math, in which all numbers are expressed as combinations of ones and zeros and are represented electrically in terms of on and off impulses. Others, known as linear, or analog, devices, eschew the binary system in favor of electrical relationships based on proportional inputs and outputs. A digital watch uses binary math; an ordinary timepiece, which marks the passage of time with rotating hands, is an analog device.

  Many electronic systems use both digital and analog equipment. An ordinary telephone, for example, might be hooked up to a computer, a heat-sensing device to a microprocessor. Since neither the telephone nor the heat-sensing device are digital machines, we need equipment that can mediate between them and their digital counterparts.

  The chip on the opposite page is such a mediator. It converts incoming digital signals into outgoing analog voltages. For instance, it might convert a digital 101 (the number 5), or on-off-on, into a 2-volt output; a digital 1010 (10) into a 4-volt output. Analog-to-digital converters operate on the same principle, of course, but in reverse, translating incoming voltages into outgoing digital pulses.

The DAC-08 can convert an 8-bit binary input into a corresponding analog output in 135 billionths of a second. The chip has about a hundred bipolar transistors and forty resistors. The transistors are the dark green circles and small rectangular pads with the grainy brown features inside them; the grainy brown elements are aluminum connectors. The company's name and chip copyright may be seen along the upper edge. Actual size: 0.062 x 0.085 inches. Photo of


©Copyright Stan Augarten
This book is provided for general reference. The National Museum of American History and the Smithsonian Institution make no claims as to the accuracy or completeness of this work.

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