Intel BCD opcodes
The Intel BCD opcodes are a set of six x86 instructions that operate with binary-coded decimal numbers: AAA, DAA, AAS, DAS, AAM, and AAD. Most arithmetic operations on x86 processors use a binary numeral system, but these instructions allow basic arithmetic using a decimal numeral system. In addition, the x87 part supports a unique 18-digit (ten-byte) BCD format that can be loaded into and stored from the floating point registers, from where ordinary FP computations can be performed.