Binary-coded decimal Binary-coded decimal In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are sometimes used for a sign or for other indications (e.g., error or overflow). In byte-oriented systems (i.e. most modern computers), the term "unpacked" BCD usually implies a full byte for each digit (often including a sign), whereas "packed" BCD typically encodes two decimal digits within a single byte by taking advantage of the fact that four bits are enough to represent
Byte order mark as a byte sequence in various encodings and how those sequences might appear in a text editor that is interpreting each byte as a legacy encoding (CP1252 and caret notation for the C0 controls): Byte order mark The byte order mark (BOM) is a Unicode character, , whose appearance as a magic number at the start of a text stream can signal several things to a program reading the text: BOM use is optional. Its presence interferes with the use of UTF-8 by software that does not expect non-ASCII bytes at the start of a file but that could otherwise