I have applied my last changes correcting the bug in dgbselect() to it
and here is the patch. Submit it please. Thank you!

BTW, there is a new option "NDGBPORTS". By default it is equal to
NDGB*16 and means the number of ports of all Digiboards for which the
tty structures are reserved. It can be set to the real value in config-file
like:

options "NDGBPORTS=8"

Submitted by: Serge A. Babkin <babkin@hq.icb.chel.su>