1. A computer program product for executing a convert machine instruction in a central processing unit, the computer program product comprising: a tangible computer readable storage medium, readable by a processor and storing instructions for execution by the processor for performing a method comprising: executing the convert machine instruction, the convert machine instruction being defined for computer execution according to a computer architecture and comprising an opcode, one register field, and another register field, the executing comprising: performing a convert from function defined by the opcode of the convert machine instruction, said convert from function comprising: converting a value, obtained from at least one register designated by the one register field from one format to a decimal floating point format, wherein the converting comprises: creating a working format of the value, said working format being different from the decimal floating point format; and using the working format to produce the value in the decimal floating point format; and placing a result of the converting in at least one other register designated by the another register field.