archive.org almost has some info:
http://web.archive.org/web/19990908232518/http://www.setasi.com/DECPP.html
It's a "Super Cache". Perhaps you could track down someone from Setasi?
See the mention here:
ftp://ftp.dbit.com/pub/pdp11/faq/faq.pages/vendors.html
/P
On Wed, Sep 23, 2015 at 02:40:14PM -0700, Josh Dersch wrote:
Hi all --
I just added a PDP-11/44 to my collection and it appears to have some
manner of cache upgrade; it's made by Digital Data Systems (DDS) and
consists of two cards, one hex-height labeled "SC44 SETASI" (in the place
of the normal 11/44 cache board) and a second quad-height labeled "1051" at
the end of the first backplane. The two are connected via a ribbon cable.
I know DDS made some seriously nice upgrades for the 11/70 but I can't find
anything on this board set at all. I'm assuming it's just a souped-up
cache but it'd be nice to know more (and docs would be excellent of course).
Thanks,
Josh