Difference between CIO and SIO

Question: When I select DDR-II family of SRAM's,I can choose between CIO and SIO. What is difference?

 

Answer:

CIO stands for "Common Input Output". SIO stand for "Separate Input Output". In CIO, common bus is used for reading and writing in memory, so you cannot read and write simultaneously. Where in SIO, separate bus is there for reading and writing, so you can do simultaneous reading and writing.