  Fast parallel search capabilities on large datasets provided by content
addressable memories (CAM) are required across multiple application domains.
However compared to RAM, CAMs feature high area overhead and power consumption,
and as a result, they scale poorly. The proposed solution, DRAMA, enables CAM,
ternary CAM (TCAM) and approximate (similarity) search CAM functionalities in
unmodified commodity DRAM. DRAMA performs compare operation in a bit-serial
fashion, where the search pattern (query) is coded in DRAM addresses. A single
bit compare (XNOR) in DRAMA is identical to a regular DRAM read. AND and OR
operations required for NAND CAM and NOR CAM respectively are implemented using
nonstandard DRAM timing. We evaluate DRAMA on bacterial DNA classification and
show that DRAMA can achieve 3.6 times higher performance and 19.6 times lower
power consumption compared to state-of-the-art CMOS CAM based genome
classification accelerator.
