1. A method of executing a machine instruction in a central processing unit, the method comprising: obtaining, by a processor, a machine instruction for execution, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising: at least one opcode field to provide an opcode, the opcode identifying a convert from zoned to decimal floating point function; a first register field designating a first operand location; a second register field and a displacement field, wherein contents of a second register designated by the second register field are combined with contents of the displacement field to form an address of a second operand; and a sign control used to indicate whether the second operand has a sign field; and executing the machine instruction, the executing comprising: converting the second operand in a zoned format to a decimal floating point format; and placing a result of the converting in the first operand location.