Abstract: A loader which itself may be implemented in firmware, being permanently resident within a read-only microinstruction memory in a microprogrammable digital processor, or which may be implemented by a hardwired digital logic equivalent, is provided for binding the firmware structure of such microinstruction processor at user-program, load-time. This loader is preferably activated by the loading operation to read the loaded program's operating requirements and to equate these to system requirements and to firmware controller requirements. The loader may then call upon a library of firmware which may be optionally incorporated into the system, to select the specific firmware modules which are needed to execute that particular program, and to bind the selected firmware into the processor's microprogram read-write memory.