Increase RAM memory

Hi, my project need at least 1Mb ram. variables change in running program. so i do not can use FLASH or EEPROM ram!( it's may i don't can)

How to can i Increase micro ram?

Go with external SPI RAM. http://www.digikey.com/product-search/en?pv276=17&FV=fff40027%2Cfff80434%2C2380071%2C268001d&k=sram&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25 You'll need 8 of them. Can use a simple demux chip to select which one data is active. http://www.digikey.com/product-search/en?vendor=0&keywords=74hc138&stock=1

thanks