Editing Endianness (section)

=== Variable-length data ===

Most instructions considered so far contain the size (lengths) of their [[operand]]s within the [[operation code]]. Frequently available operand lengths are 1, 2, 4, 8, or 16 bytes. But there are also architectures where the length of an operand may be held in a separate field of the instruction or with the operand itself, e.g. by means of a [[word mark (computer hardware)|word mark]]. Such an approach allows operand lengths up to 256 bytes or larger. The data types of such operands are character strings or [[binary-coded decimal|BCD]]. Machines able to manipulate such data with one instruction (e.g. compare, add) include the [[IBM 1401]], [[IBM 1410|1410]], [[IBM 1620|1620]], [[System/360]], [[System/370]], [[ESA/390]], and [[z/Architecture]], all of them of type big-endian.