>Is there any support for a PMAG-A in 1.3?

Yes, there is.

>Boot output reports it as a mfb.  Using the mfb server just does not work. 
>Using the cfb server results in a quasi-usable display, but the head on this
>particular machine (5000/120) is one of those greyscale dec monsters
>(VR319-DA).  The web page makes no mention of it, and I'm not entirely sure
>just what the heck a PMAG-A is....

It's a 1280x1024 x 1-bit-deep mono display with an 8-bit stride
between pixels.  Use the Xcfbpmax server, as recommended by
/usr/X11R6/bin/README.pmax.  (The Xmfbpmax server is only used on the
one-bit-deep, one-bit-stride 2100 and 3100 framebuffers).

(Should this go in an FAQ also? It is in the README.pmax file....)

Historically, even X11R6 on Ultrix gets horribly confused by the 8-bit
stride on these displays and mangles bitmap data and SHAPE (oval or
round buttons) horribly: the round edges are stretched to 8x the size
they should be and you get black-on-black or white-on-white
rendering:)

Is that what you're seeing?