<From: der Mouse  <mouse@Rodents.Montreal.QC.CA>
<This sounds suspicious.  16M is 22 bits.  Aren't Q-bus addresses 22

Qbus is 22 bits address and 4mb!  It takes 24bits to address 16mb.  Also the 
LANCE chips was not used on Q-BUS( is not a componenet of DEQNA or DELQA).

The Lance appeared in the non-bus boxen such as the VS2000, 3100-, and 
VAXmate.  I believe it's existance is spawned from the PC market and was
DMA limited to the then generous 16mb space of the systems of the time. 
It takes a lot of BITS, PINS or muxing to go for larger address spaces.
The idea of more than 16mb in a non mainframe scale system is relatively 
recent.

Allison