On Thu, Mar 1, 2018 at 9:04 AM, Paul Koning via cctalk <cctalk@classiccmp.org> wrote: > That's true when the MMU is disabled; if so it supplies 1 bits for the upper > bits for page 7, > and zeroes for the other pages. But if the MMU is enabled, all mapping goes > through its mapping > registers, and page 7 is no longer special. By software convention, kernel > data page 7 is > configured to point to the I/O page, but that isn't required. If you wanted > to be be perverse you > could map the I/O page via page 6 and confuse a whole generation of > programmers.
So if the I/O page is completely (all processor modes) unmapped is there any way to recover besides a power cycle? Does the RESET instruction disable the MMU? -chuck
