can I do write operations to the SDRAM directly using the JTAG UART core? I am using Cyclone II DSP development kit, and I want to load a video to the DDR2.
No, but you could do something similar with system console (http://www.nioswiki.com/index.php?title=systemconsole). See its page on the Nios Wiki for more information.There's even a low-level Java API! Cheers, - slacker