The Arduino Uno has only 2kB of RAM for both program variables and program data making it a precious resource which can be quickly filled. In programs that require additional storage an external RAM chip can be used to extend the usable storage space. This video discusses using a Microchip 23LC1024 serial RAM chip to create this extra storage.
A document that fully explains both the wiring of the chip and the example program is here:
https://drive.google.com/open?id=0B_fbeWIk_tZVSjlXRTNBUlRobmc
The Arduino sketch for the example program is here: https://drive.google.com/open?id=0B_fbeWIk_tZVZzEwcUNVNHFhTUk
