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nikey22
 Post subject: WD1001FALS Rom dump comparison
PostPosted: February 26th, 2022, 16:48 
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Joined: February 18th, 2022, 16:54
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Location: Canada
I'm curious, I have 2 hard drives nearly identical, infact the serial number is only 8 digits behind the other one. Yet, in the ROM dumps, I still see some differences in the preamp values and microjogs. What are those? What do they mean?

P.S. swapping out the ROMs between the 2 drives, they both read fine and behave 100% normally. Thanks!
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labtech
 Post subject: Re: WD1001FALS Rom dump comparison
PostPosted: February 26th, 2022, 19:47 
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Joined: August 18th, 2010, 17:35
Posts: 3630
Location: Massachusetts, USA
https://blog.acelaboratory.com/tag/microjogs

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fzabkar
 Post subject: Re: WD1001FALS Rom dump comparison
PostPosted: February 26th, 2022, 20:34 
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Joined: September 8th, 2009, 18:21
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HDD from inside: Tracks and Zones:
http://hddscan.com/doc/HDD_Tracks_and_Zones.html

The following patent document has a good explanation of microjogs:
http://patentimages.storage.googleapis.com/pdfs/US5978168.pdf

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nikey22
 Post subject: Re: WD1001FALS Rom dump comparison
PostPosted: February 27th, 2022, 0:41 
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Joined: February 18th, 2022, 16:54
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@labtech
@fzabkar
thank you both, those were excellent reads. I have a new appreciation for these intricate devices!
I heard there are modules in the SA that will re-compute the mircojogs for you, to optimize throughput? Any thoughts on this? Thanks.
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