I needed to do a MAKEDEV of scc0 which made tty0 and tty1 as 
17,2 and 17,3.

One bug in the MAKEDEV script: the serial ports are actually
17,0 and 17,2 so tty0 and tty1 should be those major,minor pairs
and not 17,2;17,3

One puzzling thing is that I get silo overflow and never get a complete
ppp connection made.

yf