A central processing unit (CPU) 10 comprises an external control memory for storing microinstructions which correspond to macroinstructions read from a system memory. The microinstructions are 56 bits in length and are read in 28-bit segments. CPU 10 also comprises an internal memory management unit...http://www.google.fr/patents/US5404560?utm_source=gb-gplus-shareBrevet US5404560 - Microprocessor having external control store
