an ugly bit where we record the value of a2 while handling a "nofault" bus
error in locore.s in order to know how far the transaction got before a
disconnect (see esp.c comments for more details on this).
Also get rid of a loop (and delay()!) in the interrupt routine--hinted at
and researched by Chas Williams <chas@cmf.nrl.navy.mil>.
but is a marked improvement. This takes advantage of a pseudo-DMA hardware
hack of Apple's that exposes a 16-bit register that the Apple-designed
memory controller acts like a DMA controller and handshakes into or out
of the FIFO. Wierd.
some guesses for the machines that have two of these buggers (I don't have
such a machine). This driver is a copy of the sparc/alpha esp with a
minimum of changes--after we get it performing a bit more respectably,
we should see about re-normalizing the sources.
