Date   : Wed, 15 Mar 2006 11:51:37 +0100
From   : John Kortink <kortink@...>
Subject: Re: SASI/SCSI <>IDE, distracting thoughts.

On Wed, 15 Mar 2006 10:39:02 +0000, Jules Richardson wrote:

>[...]
>
>Problem AIUI is that ADFS just won't cope with anything other than 256 byte 
>sectors at the lowest level (although isn't the ADFS filesystem format 
>permanently fixed at 256 bytes/sector too?)
>
>Out of interest, how's this been addressed with the various IDE projects out 
>there? Presumably IDE drives have the same sorts of problems, and are probably 
>fixed at 512 bytes/sector without a LLF? Is half the disk being thrown away, 
>or has ADFS been patched so it can address a high/low half of a 512 byte 
>sector as a 256 byte one?

It'd be easy to fix by throwing away half the 512-byte
sector as appropriate (i.e., worst case, at the start
and end of every transfer). In GoMMC it is solved in a
more generic way to provide byte level access (any
partially accessed sector is buffered first, then the
relevant bytes are copied out, or they are overwritten
before the sector is written back). It's quite easy to
fix at the software level.


John Kortink

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