I just fixed an old bug (pr #4174) in sys/arch/pmax/dev/bt459.c.  It
works just fine for me on a CFB, but the same code is used in the pmax
SFB driver, too.  I don't think this breaks anything, but this is a
heads-up just in case.  This is the same basic bug that also showed up
in the mfb driver; kudos to Michael Hitch for spotting it, once we'd
narrowed down the bug to the colormap ioctl.

With the fix, you can force a TC DECstation to use a remote serial
console by doing

	>> setenv console s

in the PROM, but still use the framebuffer and keyboard for rcons or
an Xserver, as long as the hardware is present and the kernel is
configured with the appropriate drivers.

(On 3100s you have to physically pull the video RAM, so this trick
doesn't work.)