[ ... serial console doesn't worok with DECstation 5000/200 ... ]
| Another thing:
| All three TurboChannel-Slots had cards in them. The first one is labeled
| parallel port and has an appropriate Sub-D connector, but I have no idea
| what the two others are good for. The second one has no connectors to the
| outside and is labeled Image ACC Daughter Board. The third one is labeled
| UHRFB Duaghter Board and has two 15-pin Sub-D connectors to the outside.
| Any ideas?

I've browsed ULTRIX/Digital UNIX /sys/data directories, but could not
find out the possible candinate.  At least your 200 seems not equipped
with any of frame buffer devices, so connecting keyboard might confuse
the machine.  IOASIC DECstation PROM works like this;

Upon poweron, PROM checks 'console' variable. If it was 's', PROM uses
serial console.  If not 's' ('*' is appropriate because it will mean a
wildcard), AND there is keyboard attached, PROM searchs a TURBOchannel
frame buffer which resides in lowest numbered TURBOchannel slot (PROM
allows multiple frame buffer configuration).  If PROM could not find
out a keyboard, PROM uses serial console regardless of console
variable.  I don't know what will happen in case of 1) console
variable has a value other than 's' 2) keyboard is attached 3) but
there is no frame buffer.  I'm wondering that the machine configuration
is same as it was in service...

Tohru Nishimura
Information Technology Centre
Nara Institute of Science and Technology