DEC pdp 11 "R-K ABBR. BOOT P. C. Board"

[william degnan]

What is the purpose of this controller?  It came with a PDP 11/05 system:
http://vintagecomputer.net/digital/PDP11-05/dec_r-k_abbr_bootPC_Board-a_front.jpg

Printed on the controller is
R-K ABBR. BOOT P. C. Board 609395 Rev B
802000 Rev

I searched around, found nothing specific  Is this a bootstrap board for an
RK drive?

-- 
Bill
vintagecomputer.net