Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!gatech!ncsuvx!shumv1!unkydave
From: unkydave@shumv1.uucp (David Bank)
Newsgroups: comp.sys.ibm.pc
Subject: Re: COBOL, power cycles, and hard disks
Keywords: COBOL for PCs, acceptable power cycling, manual disk parking
Message-ID: <4274@ncsuvx.ncsu.edu>
Date: 22 Oct 89 20:20:23 GMT
References: <4005@cbnewsc.ATT.COM> <4267@ncsuvx.ncsu.edu> <6626@pt.cs.cmu.edu>
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Reply-To: unkydave@shumv1.ncsu.edu (David Bank)
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In article <6626@pt.cs.cmu.edu> ralf@b.gp.cs.cmu.edu (Ralf Brown) writes:
>In article <4267@ncsuvx.ncsu.edu> unkydave@shumv1.ncsu.edu (David Bank) writes:
>}depends on the hard disk. Check with the manufacturer to find
>}out. Generally speaking, RLL drives are intrinsically auto-park,
>}while most MFM drives are not.
>
>My MFM ST4051 is most definitely autopark.  I think the deciding factor is
>whether the head positioner is a stepper motor (nonparking) or voice coil
>(autoparking).
>-- 
>{backbone}!cs.cmu.edu!ralf   ARPA: RALF@CS.CMU.EDU   FIDO: Ralf Brown 1:129/46
>BITnet: RALF%CS.CMU.EDU@CMUCCVMA   AT&Tnet: (412)268-3053 (school)   FAX: ask
>DISCLAIMER? | _How_to_Prove_It_ by Dana Angluin
>What's that?|   2. Proof by Intimidation: "Trivial."


    Well, since RLL drives practically HAVE to be voice-coil, that
sorta proves my statement, doesn't it?????

    Fact is, I can't think of any RLL drives that use stepper motors.
Might be a handful out there. Anyone know for sure??? Maybe some
of the early ones???

    Stepper motors CAN be auto-parking. You just have to provide a
power source after the main one is shut off and instructions to the
motor to step to the landing zone. Voice-coil just returns to the
retracted position due to its design. That's why most stepper-driven 
drives aren't auto-park -- its a pain to make them do that.

Unky Dave
unkydave@shumv1.ncsu.edu