hi,smb
if you design a new subject,you'd better use a new cpu,which can derectly interface a sdram.
if you insist a cpu no such a interface,if you use a FPGA or CPLD,you can design your own sdram controller in your FPGA or CPLD.
so,you can browse the xilinx or altera website,i remember they have some info about a sdram controller.and the controller is not difficult to design.