Solution:
It is possible to use the latest driver, which ships with the card itself, all though some minor changes are required (see below).
Installation
Follow a normal OS5 installation sequence. It will fail whilst rebuilding
the kernel with an interrupt conflict with the RTC driver.
Edit /etc/conf/sdevice.d/comf and change the sixth entry on the line (first 0)
to the interrupt vector used for the first AT card.
Edit /etc/conf/pack.d/comf/space.c and add the following code fragment to the
end of the file.
tty_modem_hangup(g)
int g;
{
signal ( g, 1 );
}
Restart the installation procedure.
# mkdev comf -install
Follow the normal instructions of installation and the driver should install correctly.