A memory cartridge having a plurality of dynamic memory units includes an access conversion circuit which converts a static access signal into its inverted signal and an access control circuit which controllably switches between a signal for refreshing each dynamic unit and a signal for external access....http://www.google.com.tw/patents/US5550781?utm_source=gb-gplus-share專利 US5550781 - Semiconductor apparatus with two activating modes of different number of selected word lines at refreshing
