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From: kamath@reed.UUCP (Sean Kamath)
Newsgroups: comp.sys.apple
Subject: Re: ProDOS patch (...)
Message-ID: <6983@reed.UUCP>
Date: Wed, 26-Aug-87 20:06:18 EDT
Article-I.D.: reed.6983
Posted: Wed Aug 26 20:06:18 1987
Date-Received: Sat, 29-Aug-87 13:08:32 EDT
References: <8708241100.aa03291@SMOKE.BRL.ARPA>
Reply-To: kamath@reed.UUCP (Sean Kamath)
Organization: Reed College, Portland OR
Lines: 19

In article <8708241100.aa03291@SMOKE.BRL.ARPA> mat6013@DMZRZU71.BITNET writes:
>version  1.2).  Adding the "LDA $C08C,X" makes sense to me, but *why* was "STA
>$C08n,X" changed to "LDA $C08n,X" (n= 0, 2, 4, 6) ?  These are for turning off
>the  four  windings  of  the  stepper  motor which is responsible for the head
>seeking.  So what's the difference between a read and a write operation here ?
>                                        Matthias Kapffer

Generally speakeing, when doing things with the drive, it is safer to do
LDA's than STA's.  I con't remember exactly why they put in the LDA's on the
steppers, but it seams to me that _that_ is what really does the crashing on
5.25 disks.  I'll post a more detailed explanaition soon.

Sean

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