"Eric D. Mudama" wrote:

On Mon, Jul 12 at 13:52, Max T. Woodbury wrote:

quoted

Still, why would PIO mode be unsafe?  (I can see slower, but I don't
expect speed from this beast.  Oh well.  Thanks for the pointer.)

PIO has no data integrity check, so bogus cables that glitch the data
will not be detected.  Not sure if that is what he was talking about,
but is definitely a problem for PIO.

Huh? Unless something major has changed since the last time I looked at
DMA hardware (and it has been a few years), DMA uses the same transfer
sequence from the devices point of view as PIO.  The fact that the 
transfer is under the control of another device rather than a program 
should be transparent to the target device.  Impedance mismatches,
reflections and constructive and destructive interference caused by
cable problems don't care about who's in control of the busses.

I can see a possible problem with cache consistency causing problems
with PIO, but there are similar (abet in some sense inverted or
reversed) problems with DMA.

max