The answer is almost certainly in here?
http://bitsavers.trailing-edge.com/pdf/dec/vax/640/EK-179A-MG-001_KA640_Oct…
I don't know, I kind of assumed you checked the manual... but the Yeti's might
have eaten it ;)
--
Mark Benson
http://DECtec.info
Twitter: @DECtecInfo
HECnet: STAR69::MARK
Online Resource & Mailing List for DEC Enthusiasts.