What is this Vadic thing ?

I think that';s right. I have one. It's very much the same as a normal RK05J, but without the door,pack holder. The disk pack is fiotted when the drive is built and held down by a couple of tension srings. It still ahs only one disk and 2 heads, but has twice as many cylinders as a noraml RK05. The fact that the back is not normally removed emans that any slight run-out in the spindle is not important, since the disk will be in the same position for formatting, writing and reading. I beleive if you do remvoe the pack for any reason, you are supposed to do a low level format when you put it back in. Much of the internals are the smae as the RK05J. The heads are obviously different, you can recognise RK05F heds by the DEC convention that the high density version of somethign is blue (think of RL02 .vs. RL01 packs). The sockets on the end of the head cables are blue on RK05F heads. I assume the positioner graticule is differnet too, but I've never investigated that. IIRC the electorncis is the later RK05J stuff, but with link changes. It appears to the controller as 2 consecutive drives, each of the 'normal' RK05 geometry. -tony