I bet it definitely works (boot on XT drive) if one disables the onboard
IDE first.
The problem I see is using IDE and MFM/RLL drives at the same time,
which might prove difficult.
To boot XT drives on an AT+, one usually has to disable the IDE drives
so that the BIOS doesn't go looking there.
I really don't see where this is a problem. User level processing does not
need
hardware memory protection; it could be implemented as a strictly software
solution. For example, a table defined within the OS giving the user and the
level. Then, all memory access could interrogate this table and
