1 - Al Kossow's Bitsavers

EXPANSION OF 3242 FOR 256-CYCLE REFRESH3242RAO-RASoo-osMAo-MAsCAO-CAS A7-A 13CA7REFRESHENABLERFSHENRA7MA7ROWENABLECOuNTROWENCNf20RAO·RA7 • ROW ADDRESSCAO-CA7 • COLUMN ADDRESSESMA"0.M'A6. MEMORY ADDRESSES (INVERTED)MA7· MEMORY ADDRESS (NON-INVERTED)Adding the above circuit to those systems which utilize a 3242 allows the use of 256-cyclerefreshparts. The circuit on the following page may also be incorporated into designs using the3242A where the zero-detect output is not available.These designs are presented to demonstrate possible implementation, however, particular systemrequirements may suggest alternate circuits to optimize component layout.NOTE; The SN74LS153 may be replaced with an SN74LS352 to obtain inverted signal for allmemory addresses.-9-4