binary digit

[′bīn·ə·rē ′dij·ət]

(computer science)

bit

(1) (Built-In Test) See BIST.

(2) (BInary digiT) The smallest element of computer storage. The bit is a single digit in a binary number containing only 0s and 1s. Physically the bit is a transistor and capacitor in a RAM cell, a magnetic domain on disk or tape, a cell in a solid state drive (SSD), a spot on optical media or a voltage pulsing through a circuit.

Transmitting Bits
Bits are used as a measurement for network transmission. For example, one hundred megabits per second (100 Mbps) means that 100 million pulses are transmitted per second. See space/time.

Storing Bytes
Eight bits make up a "byte," which is manipulated as one entity. Each byte can store one alphanumeric character, one decimal digit or a decimal number from 0 to 256 (see binary number and binary values). Measurements of files, databases, storage drives and memory (RAM) are given in bytes rather than bits. See space/time, byte and word.

Storage - Making it Smaller

Making the spot or cell smaller increases the storage capacity. Today's storage drives hold staggering amounts of data compared to 10 years ago. For a fascinating storage technology that never became popular, see holographic storage.

Storage - Making it Smaller

Making the spot or cell smaller increases the storage capacity. Today's storage drives hold staggering amounts of data compared to 10 years ago. For a fascinating storage technology that never became popular, see holographic storage.

Transmission - Making it Faster

The bit is transmitted as a pulse of high or low voltage. Speed is increased by making the transistors open and close faster, illustrated here as a mechanical switch. Transmitting pulses within the computer is much simpler than over an external network where they are influenced by distance and interference. However, the telephone companies pioneered optical trunks, which overcame these limitations.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Binary Digit

(in information theory), a unit used to measure entropy and the quantity of information. An entropy of 1 binary digit (1 bit) has a source with two equiprobable messages. The term is derived from the fact that the number of binary digits determines (to an accuracy of 1) the average number of characters required to record messages from a given source in the binary code. Decimal digits (decit) are also used. The conversion from one digit to another corresponds to the change in the base of logarithms when the entropy and the quantity of information are being determined (10 instead of 2). The conversion formula is 1 decit = 1/log 2 bits ≈ 3.32 bits.