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Calculate LBA sector from cluster

 
  

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Evan
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Since: May 15, 2006
Posts: 1



PostPosted: Mon May 15, 2006 2:32 pm    Post subject: Calculate LBA sector from cluster
Archived from groups: microsoft>public>win98>fat32 (more info?)

Does anyone know how to calculate the LBA sector number given the cluster?
From the BIOS before DOS7 starts, I need to locate the start of the root
directory then load the file into memory. In my case, the boot record says
it starts at cluster 37. A physical check using diskedit shows that it is
located at sector 2228. However, my calculations put it at 2244 (16 sectors
past).

The formula I am using is RootDirectory=((ClusterNumber x
SectorsPerCluster)+(NumFats x BigSectors) + ReservedSectors) where

ClusterNumber = 37
SectorsPerCluster = 8
NumFats = 2
BigSectors = 958
ReservedSectors = 32

Thanks,
Evan
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Since: Nov 29, 2004
Posts: 22



PostPosted: Wed Dec 06, 2006 11:43 pm    Post subject: Re: Calculate LBA sector from cluster [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

First data cluster is actrually cluster 2. So substract 2 from actual
clusternumber. Cluster 0 and 1 do not exist.

--
Kind regards,
Joep

"Evan" <Evan.RemoveThis@discussions.microsoft.com> schreef in bericht
news:91B11131-AD11-4FDF-8788-411789FAF66D@microsoft.com...
> Does anyone know how to calculate the LBA sector number given the cluster?
> From the BIOS before DOS7 starts, I need to locate the start of the root
> directory then load the file into memory. In my case, the boot record
> says
> it starts at cluster 37. A physical check using diskedit shows that it is
> located at sector 2228. However, my calculations put it at 2244 (16
> sectors
> past).
>
> The formula I am using is RootDirectory=((ClusterNumber x
> SectorsPerCluster)+(NumFats x BigSectors) + ReservedSectors) where
>
> ClusterNumber = 37
> SectorsPerCluster = 8
> NumFats = 2
> BigSectors = 958
> ReservedSectors = 32
>
> Thanks,
> Evan
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