1. A method of identifying the precision of and processing of operands in a multiprecision floating-point processor comprising on a single chip an ALU and a plurality of registers for storing a plurality of said operands, each of said operands having a tag comprising one or more tag bits for identifying the precision of the operand, comprising the steps of: providing a first and a second one of said operands; providing a first and a second one of said tags which identify the precision of said first and said second operands, respectively; transferring said first and said second operands and said first and said second tags to a first and a second one of said plurality of registers, respectively; transferring said first and said second operands and said first and said second tags simultaneously from said first and said second registers to said ALU; providing a third tag; transferring said third tag to said ALU; processing said first and said second operands in said ALU under the control of said first, said second and said third tags for providing a third operand having a precision identified by said third tag; and transferring said third operand and said third tag from and to said ALU for further processing of said third operand.