On that particular cart, it's the Panasonic chip. Other carts may use different chips, and IIRC there's at least one mapper that actually has the SRAM built into the mapper chip, or at least inside the same package.
Thanks man. Would you happen to know the specifics for the Final Fantasy cart? (For example, does it save to the mapper chip? (The mapper for Final Fantasy is MMC1, if that helps))
Damn, I'm trying to draw a picture of the Final Fantasy cart and I just noticed I'm drawing the wrong board! The above is a TKROM board; Final Fantasy used an SNROM board:
You should often be able to plug the chip labels into Google and find out what parts are what. Also you see the top two (bottom in the first picture) chips are labeled -PRG and -CHR, pretty evident they're not the RAM.
I can't read the part numbers on those Sony chips, but my guess is that the one on the lower left is CHR RAM and the one on the upper right is the save RAM. They might even be the same chip.