Are you looking for a PXI board that will allow you to interface with a RAM chip?
If so you may be interested in the following KB:
http://ae.natinst.com/operations/ae/public.nsf/fca7838c4500dc10862567a100753500/f79df6929dea7e27862567900058d1fe?OpenDocument
It tels you what you must be familiar with to develope a PXI device and lists a couple of vendors which sell boards that allready interface with the PXI bus so you can develope the rest or your hardware.
If this is not what you were looking for, please rephrase the question.
Regards,
Amaury Rolin
National Instruments
Applications Engineering