D.G. Nova update (boo f'ing hoo)

[Gordon JC Pearce]

Tony Duell wrote:
>>>Didn't some winchesters use the spindle motor as a generator to provide 
>>>the emergency retraction current?
>>
>>   The drives used in PC do that and have for many years but I never saw a
>>mainframe disk drive that did.
> 
> 
> Yes, I was thinking of things like full-height 5.25" units. Larger 
> drives often had AC spindle motors which would clearly be unsuitable for 
> this trick (well, at least not simply...)
> 
> -tony
> 

I remember seeing bits of what were apparently a Wang disk drive lying 
around a mate's workshop.  It had a very funky head retract mechanism, 
with an interlock that held everything in place with the heads 
retracted, a solenoid that pulled in on power good (and dropped out on 
power fail), and a big spring with an air piston, like an air rifle, 
that was fired when the solenoid dropped out with the heads extended, 
blowing a ram on the positioner assembly all the way back.
Once this had happened, you needed to open the cover and re-cock the spring.

Gordon.