On Sat, 29 Jan 2011, Eric Smith wrote:
Tony Duell wrote about hard drives on the Lisa:
Was the HDA a 'stadnard' one for the
time? Surely Apple didn't make that
themselves. Was it, for example, the HDA from an ST412 or something.
The original 5MB Apple "Profile" drive used an HDA from an external vendor.
I'm not sure which one. I've never seen the innards of the later 10MB
Profile.
Seagate ST506 and ST412 respectively for 5 and 10MB. At least in all the
ones I've seen. I'm told that the 10MB model had a custom stepper motor
a pitch 2x finer than normal, i.e. 2 pulses were required between tracks.
This appears correct, since my attempts at using an ST412 mechanism for a
10MB unit yielded only 5MB of storage capacity (it was skipping every
other track). When I get time and energy, I'm going to tack on a simple
divide-by-two circuit (single flip-flop) and see if that does the trick.
Steve
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