DE2-115 SDRAM without NIOS

Ted,

Thanks for your thoughts. I want to write my own SDRAM controller not simply to have a working SDRAM controller, but to fully understand at a visceral, low level everything there is to know about using SDRAM and building a controller for it.

It's very interesting you mentioned the Micron models because I have been looking around the Micron site for them. I just found them at the links below.

The SDRAM in the DE2 is a a pair of ISSI IS42S16320D-7TL, in other words a 8M x 16 bits x 4 banks (512Mb) SDRAM with 7ns cycle time at CAS 3 or 7.5ns cycle time at CAS 2. Data sheet: http://www.issi.com/ww/pdf/42-45r-s_86400d-16320d-32160d.pdf

This seems to be similar to one of these Micron part numbers:

http://www.micron.com/parts/dram/sdram/mt48lc32m16a2tg-75-it?pc={428A5CC9-2A78-447E-939B-6F3A40D538C6}

http://www.micron.com/parts/dram/sdram/mt48lc32m16a2tg-75?pc={428A5CC9-2A78-447E-939B-6F3A40D538C6}

http://www.micron.com/parts/dram/sdram/mt48lc32m16a2p-75-l?pc={428A5CC9-2A78-447E-939B-6F3A40D538C6}

http://www.micron.com/parts/dram/sdram/mt48lc32m16a2p-75-it?pc={428A5CC9-2A78-447E-939B-6F3A40D538C6}

http://www.micron.com/parts/dram/sdram/mt48lc32m16a2p-75?pc={428A5CC9-2A78-447E-939B-6F3A40D538C6}

However, they aren't remotely directly similar because Micron has no banks and does only CAS 3. I don't see any Micron SDR SDRAM newer than 2004. So, alas, these models aren't particularly useful for developing against the ISSI SDRAMs. :( Any other models you know about?

From reading the ISSI SDRAM data sheet it seems CAS2 is good for things that do small random transfers all over the place and CAS3 is good for things that do large block transfers within the same segment. I'd probably implement the CAS2 initially since that seems more like my access pattern, and there really isn't much speed difference for this part anyway. (The faster parts do CAS3 cycle times much faster than CAS2.)

It's a shame ISSI doesn't provide ModelSim (Verilog) models for these that I have found or their SRAM as used on the DE2-115 either (IS61WV102416BLL-10TLI).

Thanks!