It is inefficient compared to purely base-2 number formats, but it can be useful when accurate decimal calculations are needed.
EBCDIC was derived from IBM's forms of BCD, expanded to encompass non-numeric characters.
Each decimal digit is encoded in four bits:
The other possible codes, starting with 1010, are unused and invalid.
Two digits are usually packed into a single byte, though there can be just be one digit per byte, among other possible encodings.