Daystar made a couple of revisions of the Turbo040.

The early Turbo040 had a bunch of PLDs on the main card (GAL16's and such) and it had a connector on the back (long, 2 pin wide, black connector) for an optional L2 Cache. The L2 cache was a daughter board.

Later, the Turbo040 was revised so that all the PLDs were moved into a single, large ASIC (big square chip) and the cache was moved from the daughter board to the main board and soldered down. So, on the later Turbo040 the cache is included.