BCD stands for Binary-coded decimal, which is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. BCD is useful in digital displays, where it can be difficult to manipulate or display large numbers. Since BCD treats each digit as a separate subcircuit, data manipulation in such devices becomes easier. BCDs main virtue, in comparison to binary positional systems, is its more accurate representation and rounding of decimal quantities, as well as its ease of conversion into conventional human-readable representations. Its principal drawbacks are a slight increase in the complexity of the circuits needed to implement basic arithmetic as well as slightly less dense storage. BCD was used in many early decimal computers and is implemented in the instruction set of machines such as the IBM System/360 series and its descendants, Digital Equipment Corporations VAX, the Burroughs B1700, and the Motorola 68000-series processors. Today, BCD data is still heavily used in IBM processors and databases, such as IBM Db2, mainframes, and Power6.