----- Original Message ----- 
From: "Rob Robson" <rob@silk.net>
To: "pic microcontroller discussion list" <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, March 24, 2006 6:11 PM
Subject: [EE]: the point of ATA clusters


> I'm hoping someone can answer a question that's come up in my quest to
> understand how to use Compact Flash cards in embedded applications.  If a
> card is read by specifying a 28-bit LBA sector address (which it seems to
> be), what is the point of referencing to clusters?  FAT32 allows a 28-bit
> cluster address, and stores 32-bit values in its File Allocation Table, 
> but
> it seems that you just end up converting to sectors anyway, thereby losing 
> a
> degree of addressability equivalent to the sectors-per-cluster value.  Am 
> I
> missing something?
>
> Thanks,
> RR

You only need one FAT entry per cluster, not one per sector.

Multiple sector clusters allow for multiple sector reads = better 
performance (at least on real hard drives).

Bob Ammerman
RAm Systems

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