The CXK77P36E160GB (organized as 524,288 words by 36 bits) and the CXK77P18E160GB (organized as 1,048,576 words by 18 bits) are high speed CMOS synchronous static RAMs with common I/O pins. These synchronous SRAMs integrate input registers, high speed RAM, output latches, and a one-deep write buffer onto a single monolithic IC. Register - Latch (R-L) read operations and Late Write (LW) write operations are supported, providing a high-performance user interface. Two distinct R-L modes of operation are supported, selectable via the M2 mode pin. When M2 is "high", these devices function as conventional 16Mb R-L SRAMs, and pin 2B functions as a conventional SA address input. When M2 is "low", these devices function as Error-Correcting (EC) 8Mb R-L SRAMs, and pin 2B is ignored. When Error-Correcting 8Mb R-L mode is selected, the SRAM is divided into two banks internally - a "primary" bank and a "secondary" bank. During write operations, input data is ultimately written to both banks internally (through one stage of write pipelining). During read operations, data is read from both banks internally, and each byte of primary bank data is individually parity-checked. If the parity of a particular byte of primary data is correct (that is, "odd"), it is driven valid externally. If the parity of a particular byte of primary data is incorrect (that is, "even"), it is discarded, and the corresponding byte of secondary bank data is driven valid externally. Primary / secondary bank data selection is performed on each data byte independently. Data read from the secondary bank is NOT parity-checked. Data read from the write buffer is NOT parity-checked. All address and control input signals except ZZ (Sleep Mode) are registered on the rising edge of K (Input Clock). During read operations, output data is driven valid from the falling edge of K, one half clock cycle after the address is registered. During write operations, input data is registered on the rising edge of K, one full clock cycle after the address is registered. The output drivers are series terminated, and the output impedance is programmable through an external impedance matching resistor RQ. By connecting RQ between ZQ and VSS, the output impedance of all DQ pins can be precisely controlled. Sleep (power down) mode control is provided through the asynchronous ZZ input. 250 MHz operation is obtained from a single 3.3V power supply. JTAG boundary scan interface is provided using a subset of IEEE standard 1149.1 protocol.