Arduino Mega is a great board but it is severely limited by its 8K SRAM. This dynamic RAM (DRAM) shield provides 1MByte Dynamic RAM to Arduino Mega.

What is Dynamic RAM?

Dynamic RAM (DRAM) chips are different than Static RAM (SRAM) because they use a single capacitor to hold the bit value, as opposed to using a FlipFlop in SRAM's. This single capacitor approach makes it possible to squeeze lots of bits in a small chip. This is how we can get Gigabytes of memory in today's computers. The catch is the small capacitor will leak the charge and if not "Refreshed" before the charge drops below the "Critical threshold", the cell will forget the bit value. Even the act of reading the cell value may deplete the charge. Hence DRAM chips must be refreshed regularly. We use one of Arduino Timers to do the refreshing in the background.

Features

• 1MBytes of RAM available for use.
• One of the 6 timers, selectable, does the refreshing in the background.

Negatives:

• Analog pins, A0..A15, are not usable because they are dedicated to DRAM interfacing. (A0..A7 might be usable, please read the documentation for some options)
• Interrupts can not be disabled for a long time otherwise refresh timer will not refresh the dram in time and data corruption may occur. If you need interrupts to be disabled then please perform manual refreshing.