A processing system having a processor which accesses external memory for data and/or instructions includes an improved external memory access control system producing external memory enable time durations which are independent of the number of external memory accesses per unit of time, thereby reducing...http://www.google.com.hk/patents/US5481690?utm_source=gb-gplus-share專利 US5481690 - Power-efficient external memory access control using external memory enable time durations independent of external memory accessing rate
