386i: AT-BUS / Floppydrive Interference

[Hermann Hueni]

Machine:

Sun 386i/250 w. ExpBox, SunOS 4.0.2

Nature of problem:

Interference of an add-on AT-bus-card (MIRO) with the floppy-disk.  This
problem has not been seen with SunOS 4.0.1

Symptoms:

Reading and writing to the floppydisk (from dos) is very much disturbed,
when the MIRO-card is installed. Sometimes one gets through after a couple
of retries. It seems as the MIRO-SW is using the same signal as is used by
the floppydrive.

Hardware involved:

	miro datensysteme GmbH, D-3300 Braunschweig
	16bit IBM AT compatible Graphicboard 1280x1024, 256 colors
	I/O Space 3E0h or 390h (0-F)
	Memoryspace to map the board in: CC00h - CFFFh ( or 3 alternatives )
	Interrupt: 7Fh

Questions:

What are the differences from SunOS 4.0.1 to SunOS 4.0.2 that might be
responsible for this interference?  How can we overcome this problem
without going back to Release 4.0.1?