filbo@gorn.santa-cruz.ca.us (Bela Lubkin) (09/04/89)
In article <9864@multimax.Encore.COM> Terence Kelleher writes: >If the head on one arm assembly is required to read data >that may have been writen on the other assembly, then the position of >the head must be correct when compared to either of the 2 servor >heads. This is eliminated if embedded servos are used, but other >problems arise, like limitations on the number of bytes per sector. >Lots of systems use funny sizes here and would not be able to use a >drive with restrictions on sector size. Why does embedded servo imply restrictions on sector size? (Not sarcastic; I really don't know). Hmmm. IF you can assume that each assemblage of heads is rigid, what if you dedicate BOTH the top of the top platter and the bottom of the bottom as servo platters? This lets you interpolate the positions of intermediate heads. I don't know what the tolerances are on head alignment, but it seems like that would work. >If I'm not mistaken, the NEC 9 in drive does use 2 head assemblies on >each arm. I'm not sure why, but its seek time does not look any >better than other 9 in drives. Maybe they found it cheaper to use two heads and a slower seek mechanism? Sounds silly to me, though... >Terry Kelleher, Encore Computer Bela Lubkin * * filbo@gorn.santa-cruz.ca.us CIS: 73047,1112 @ * * ...ucbvax!ucscc!gorn!filbo ^^^ REALLY slow [months] R Pentomino * Filbo @ Pyrzqxgl (408) 476-4633 & XBBS (408) 476-4945