mef> But Tanzania machine now only runs with serial console.
mef> That's should be true, either ttya or ttyb.

To be more confusing, sorry, this does not mean you can't
access kbd/screen.

You may use kbd/screen even on Tanzania box if:
(1) boot from input/output-device as ttya
(2) have wscons=YES line in /etc/rc.conf
(3) have uncomment screen0 line in /etc/wscons.conf
(4) (make sure you have ttyE0 line on on /etc/tty),

you can login from the kbd/screen.
---
Makoto Fujiwara,