I fixed MX issue and placed new netbsd.wscons.gz file at
~ftp/pub/NetBSD/arch/pmax/WSCONS/ directory of NetBSD ftp site.

MX is the pecularity of which screen width (1280) is smaller than the
scanline stroke 2048.  All other DECstation framebuffers have the same
size of scanline as screen width.  That was the reason why I have not
been aware of the bug in dev/rasops/rasops.c.

Tohru Nishimura