 The IBM System/370 includes a facility called "Initial-Microprogram Load" ("IML" or "IMPL") that can be invoked from the console, as part of "power-on reset" ("POR") or from another processor in a tightly coupled multiprocessor complex.Some commercial machines, for example IBM 360/85, have both a read-only storage and a writable control store for microcode.WCS offers several advantages including the ease of patching the microprogram and, for certain hardware generations, faster access than ROMs can provide.