>Can NetBSD/pmax be used on a DECstation without framebuffer, with console
>on the serial-port e.g.? 

Yes, of course it can. On a 5000 series mahine, do

     setenv console s
and that redirects the PROM console to the serial port.
To set it back, do
    setenv console c

(or anything else except 's').

>Somebody I know stated that NetBSD won't boot
>without a supported framebuffer. Could one of you give me an update
>on that.

Whoever told you that was mistaken. There were problems booting with
framebuffers that are *not* supported, but I think that is fixed too.

> We'd like to use a DECstation with NetBSD for a WWW-server
>(their framebuffers are not supported by NetBSD, I understood) so
>don't need X-support for these machines.

Only the PMAG-C (acceleratd 2-d), the PMAG-D, E, and F range (with
onboard i860 blitter) and the PMAG-J (24-bit truecolour) are not
supported.  You should still be able to boot your machine with one of
those framebuffers inserted.

In particular, the baseboard video on the Personal Decstation
(5000/xx) _is_ supported by NetBSD.  If someone told you
otherwise, they're wrong.