i've had this idea in the past.

if you have 8 banks of 80ns ram and rotated the active bank then writing
every 10ns could be done. this would give the required 80ns to setup the
memory for the next write. yes it does require alot of hardware, but it's
alot easier to buy a bunch of 80ns memory than it is to buy one 10ns memory.

just a thought. (if your totally confused, tell me and i will better
explain)

michael