Who's is bigger? was RE: [SunRescue] Re: NetApps?

[rescue at sunhelp.org]

>Question:  the platters were 12 or 13 inches across, right?

   The inner diameter of the coated area was 4.25 inches, and the outer
diameter of the platter was 10.5. I just measured the one I have hanging
on the wall here in the office. The upper surface of the topmost platter
was not used. The lower surface of the bottommost platter was used
differently, probably for servo tracks. The other surfaces each had two
heads per surface, attached to the same arm at a fixed offset from each
other, to reduce the amount of arm travel required to access a track. I do
not think that the areas overlapped -- i.e. there were no tracks that
could be accessed by two heads. When you consider that the head/arm assembly
weighs about a pound, it makes a lot of sense to reduce head motion!

   --James B.