What are the various interfaces used on memory devices

Question

There are various external memory devices for temporary and permanent storage of data. This may have interface as simple as RD/WR signal with data-address bus and chip select with output enable. However, more complex memory devices have a more complicated interface and need a state machine on the processor side to keep track of what state the memory is in e.g the DDR RAMs.

Is there some application note or website that gives list of various type of memory devices in terms of complexity of interface and explain how is each controlled via the interface?

Answer 1

Various memory devices are in general covered by JEDEC standards. You may find them on their official website. DDR1/2/3, CFI (for flash memory) are covered by their standards.

It may be really useful to go through data-sheets of the chip manufacturers to better understand some details. I would go with excellent data-sheets of Samsung (DRAM, flash), Spansion (flash), Freescale (processors that access these memory devices). You may find all of them on the Internet for free.

Answer 2

You can split the various interfaces used on memory devices into 2 large classes: parallel access and serial access. There are so many different kinds of parallel and serial access interfaces that it is impossible to give a complete answer without writing a multi-page report.