An auxiliary video board (AVB) has
been developed that will allow 64 & 128 users an additional 80 col. display
ability.  The AVB was designed using the C-8564VDC chip used in the 128 and
has 64k bytes video memory which can be used as extra ram.  It is compatible
with the 1750.  With the AVB plugged into the 128s expansion port, two 80 col.
hi-res video displays can be operated independantly displaying text and or
graphics.

The programming is very simple and allows both displays to use a commen set of
screen subroutines.  The AVB is powered by +5vdc from the expansion port with
less than 300ma of current.  On the 64 and additional source of regulated
power is needed.  

The AVB is constructed from off the shelf parts for around $70.  A blank pc
board with complete assembly instructions, board options, parts list and
programming expamples is available for $39 from:
Gregory Clark, PO Box 660366,  Sacramento CA 95866-0366.

I got this from Boise User Group Newsletter, Bug Bytes, by Doug Parsons.
What about it DB?