180MHz 8ns 256K x 18 4Mb pipelined and flow through synchronous NBT SRAM 180MHz 8ns 256K x 36 4Mb pipelined and flow through synchronous NBT SRAM 150MHz 10ns 256K x 36 4Mb pipelined and flow through synchronous NBT SRAM 166MHz 8.5ns 256K x 36 4Mb pipelined and flow through synchronous NBT SRAM 150MHz 10ns 256K x 18 4Mb pipelined and flow through synchronous NBT SRAM