The first ending tablebases - for all 4-piece endgames - were built by the end of the 80-s. In the beginning of the 90-s, the same task was done for 5-pieces. In 2005, 6-piece endings were solved in Nalimov Tablebases which are now used by many professional chess programs and services.
Experts didn’t expect 7-piece endings to be cracked and catalogued until after 2015, but Convekta Ltd, namely programmers Zakharov and Makhnichev - the developers of the Aquarium interface - managed to solve this task in just 6 months using a new algorithm designed specifically for this purpose and run on the Lomonosov supercomputer based in the Moscow State University.
As a result, we now have 525 tablebases of the 4 vs. 3 type and 350 tablebases of the 5 vs. 2 type. The calculations for 6 pieces playing against a lone king weren’t done because the outcome is rather obvious.
The total volume of all tablebases is 140 000 gigabytes, which is obviously too much for personal computers. Lomonosov Tablebases will be accessible online from the Aquarium interface and on the chessok.com website. All users of ChessOK Aquarium, Houdini Aquarium and Chess Assistant products get free access to the service for the period specified in their product description.