The KM44C16100BK-6 are 16M X 4, i.e., four bits wide with 16M addresses. Because there are 16M addresses, this requires 24 bits, which means the row/column organization must be 12 X 12. A 12 bit row address gives the 4K designation, as the 1K, 2K, 4K designator is just the number of row addresses, corresponding to 10 bits, 11 bits or 12 bits of row addresses.
Eight of these chips (one side of the D4893A SIMM) gives 64 MB of capacity. 16M X 4 X 8 (chips) = 16M X 32 bits and 1 byte = 8 bits => 4 bytes = 32 bits. So 16M X 32 bits = 16M X 4 bytes = 64MBytes.
Two sides to the SIMM gives 64MB X 2 = 128 MB.
I used two of the KM44C16100BK-6 to build each of my 16MB IIfx SIMMs.
Oh, and a thing I meant to mention a year ago... I've used two of the 128MB SIMMs in a SIMM doubler to take the Q605 up to 260 MB of RAM. I'm not quite sure how that works, as I wouldn't have expected there to me enough RAS lines in the Q605. One of these days I'll dig out the SIMM doubler again and trace it's circuitry.