[Coco] DE-1 Expansion Board Project - I need a suggestion

[sales at gimechip.com]

Hey folks:
I've finished the 1Mx16 (2-meg total) SRAM design for the DE-1 Expansion board. I've also included the Analog Joystick circuitry as per Gary's request.

I had originally intended to include a battery backup for the SRAM. However, at present, I have removed it from the design. The reason being that the ISSI RAM chip specifies a 3.3V power source in order to operate at 8nS, which is important to the CC3FPGA project. The battery backup circuit introduces sufficient voltage drop to force the SRAM to it's 10nS access time. However, Gary suggested that I ask all of you if you might want the battery backup circuit added. If I add it back to the design, there would be a jumper to enable it, in which case the RAM would have a 10nS access time, battery backup disabled would allow 8nS. Let me know your thoughts.

Once I get the feedback on the battery backup, I'll finish the layout and send it to Gary for inspection. Thanks for any input - John

P.S. - I might to a similar board for the Spartan, since I have one of those - I don't have the DE-1 yet but I'm leaving Dad little notes around the house: i.e. "Wouldn't you like to buy your son a DE-1?" - hey, it worked when I was 7 :-)