Documentation from Altera:
Go to their literature page: http://www.altera.com/literature/lit-nio2.jsp
Click on (zipped) Embedded Documentation One-Click Download for the version of Quartus you have.† Install this in a folder for future reference.† These are your only documents about how to add memory.
Memory chips on the DE2 Development Board
This board is made by Terasic
Flash memory is a 4MB chip by Spansion: S29AL032D.††
Company webpage and data sheets: http://www.spansion.com/Products/Pages/ProductDetails.aspx?ProdID=S29AL032D
SRAM 512 KB is by ISSI Integrated Silicon Solution, Inc.† website: www.issi.com†
Part # IS61LV25616AL-10TL†† Search of company database turns up several similar chips, closest chip is IS61LV256ALÖ http://www.issi.com/pdf/61LV256AL.pdf† This is a Low Voltage high speed CMOS.† The *.pdf† states itís a 32K x 8 and interprets that to mean 32,768 word by 8 bit static RAM.† Based on the DE2 board label, 512 KB and the 16 in the part # we could assume that this is a 32K x 16 or 32,768 word by 16 bit static RAM.† There is other good info in the PDF about the control lines.
SDRAM 8MB is by PSC †Powerchip Semiconductor Corporation www.psc.com.tw/english
Part #A2V64S4OTCP† website link to SDRAM chips: http://www.psc.com.tw/english/product/product_1c.html††
Things change fast in this business, company is now called Powerchip Technology Corporation.