The UT7C138 and UT7C139 are high-speed radiationhardened CMOS 4K x 8 and 4K x 9 dual-port static RAMs. Arbitration schemes are included on the UT7C138/139 to handle situations when multiple processors access the same memory location. Two ports provide independent, asynchronous access for reads and writes to any location in memory. The UT7C138/139 can be utilized as a stand-alone 32/36-Kbit dual-port static RAM or multiple devices can be combined in order to function as a 16/18-bit or wider master/ slave dual-port static RAM. For applications that require depth expansion, the BUSY pin is open-collector allowing for wired OR circuit configuration. An M/S pin is provided for implementing 16/18-bit or wider memory applications without the need for separate master and slave devices or additional discrete logic. Application areas include interprocessor/multiprocessor designs, communications, and status buffering.