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From: Don.Noll@p3425.f421.n109.z1.Fidonet.Org (Don Noll)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Problems with Quantum LPS52
Message-ID: <672105041.1@blkcat.Fidonet.Org>
Date: 19 Apr 91 23:09:24 GMT
Sender: Usenet@p0.f40.n109.z1.Fidonet.Org
Lines: 33


 
PH> Just a follow-up to this message.  I contacted tech-support at the place
PH> I 
PH> ordered this disk and got more information.
PH> 
PH> When I ordered this disk, I specified mounting hardware for a Mac II.  It
PH> 
PH> turns out that the disk is also formatted for a Mac II, and cannot be
PH> used 
PH> on a slower mac.  Furthermore it cannot be reformatted to be used with a
PH> 
PH> slower mac--doing so "blows the EPROM" or something like that.  It has to
PH> 
PH> be sent back to the factory.
PH> 
PH> Sure enough, the disk runs without crashing on my mac II, but crashes on
PH> 
PH> my mac plus.  The vendor is going to replace the disk with one formatted
PH> 
PH> for a mac plus.
PH> 
PH> Moral:  there seems to be some problem with reformatting these disks for
PH> 
PH> slower computers.  Be sure to get one formatted for the slowest computer
PH> 
PH> you will use it with.
PH> 

Professor, the difference betwwen the formatting on a Plus and a Mac II is in the INTERLEAVE.  The Plus <Without help from a read ahead cache> will still read a disk formatted for a MacII but at a reduced speed.  The formatting software they are selling with the drive SHOULD be able to change the interleave itself.  An eprom on a SCSI drive is an interesting idea, but I think the ROM in the machine is the problem. Suggested interleave factors for macs are as follows,
1/1 for MacII and faster(including SE/30), 2/1 for SE, 3/1 for a Mac Plus.

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