1. A system for adding reconfigurable computational instructions to a computer, the system comprising: a processor operable to execute a set of instructions of a computer program comprising a set of computational instructions and long instruction word instructions with at least one of the long instruction word instructions comprising an instruction extension; an extension adapter coupled to the processor and operable to detect the execution of the instruction extension; and programmable logic coupled to the extension adapter and operable to receive configuration data for defining the instruction extension and execute the instruction extension.