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, wherein the converting comprises: converting one or more triplets of zoned digits in the second operand to a corresponding one or more densely packed decimal groups, the corresponding one or more densely packed decimal groups provided as a first portion of a result; and converting a remaining zoned digit in the second operand to a corresponding bit sequence, the corresponding bit sequence being provided as a second portion of the result; and placing the result in the first operand location, wherein the result is stored to the location in the decimal floating point format absent issuing one or more additional machine instructions to convert to the decimal floating point format.