Changes necessary for wscons on NetBSD/pmax. All device support is here,
just needs further testing.
Remove debugging crud.
Bail out if dt_identify() fails.
More sanity checks.
Some fixes.
Sanitize.
Remove some more debugging crud, and use the full screen.
- Attach keyboard/mouse only on 3MAX and PMAX.
- The mouse needs 8-bit characters, not 7.
Minor tweaks.