Sorry, I've been asleep at the keyboard. See:
<http://dundas-mac.caltech.edu/~dundas/retro/DEC
Docs/PDP-11/Unibus/ed-23181-10_A1b.pdf>
John
--
John A. Dundas III
Director, IMSS Voice & Data Networks, Caltech
Mail Code: 1-10, Pasadena, CA 91125
Phone: 626.395.3392 FAX: 626.449.6973