The 2147 was a mainframe cache static memory chip. It is extremely fast, I
think in the 35 nSec range, and uses less power than most of the static
memory chips more commonly used in S-100 systems, although being a static
memory chip, it is not "low power" by any stretch of the imagination.
My recollection is that it's a 4kx1 chip with the same pinout as the TI 4044
and almost all of the other 4kx1 static memory chips, and that you can
actually substitute or mix 4044's and 2147's (the 4044's are nothing like as
fast, but in a 2 to 4 MHz S-100 system, you only need 150 to 250 nSec).
However, please check this out, as it's possible that the 2147 was 1kx4
instead of 4kx1.
I don't know why no one else used this chip, but it is a fantastic static
memory chip.