FDC Reading

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bino78
Posts: 2
Joined: Sat Jul 30, 2011 8:44 am

FDC Reading

Post by bino78 »

Hello, I followed the documentation in wiki.OSDev.org about FDC and I wrote a simple program which reads a track. I thought that by the direct access to the FDC (without the use of INT 13h) I would have been able to obtain not only the data, but also the IDAMs and the other info that are stored in the track when it is formatted. Contrarily, the output was analogous to the one by INT 13h: no IDAMs, no bytes stored in the GAPs and so on. I tried to specify a different sector size and different GAP1 sizes, but everything failed.
My question is: do exist tricks that allow to read everything is stored in the track? Thank you very much.
Casm
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Posts: 221
Joined: Sun Oct 17, 2010 2:21 pm
Location: United Kingdom

Re: FDC Reading

Post by Casm »

bino78 wrote:Hello, I followed the documentation in wiki.OSDev.org about FDC and I wrote a simple program which reads a track. I thought that by the direct access to the FDC (without the use of INT 13h) I would have been able to obtain not only the data, but also the IDAMs and the other info that are stored in the track when it is formatted. Contrarily, the output was analogous to the one by INT 13h: no IDAMs, no bytes stored in the GAPs and so on. I tried to specify a different sector size and different GAP1 sizes, but everything failed.
My question is: do exist tricks that allow to read everything is stored in the track? Thank you very much.
Address marks are only visible to the floppy disk controller. They cannot be read by software because there is no obvious reason why it would need to (and it would be a bloody nuisance if, after every 512 bytes, metadata intruded itself into the data which is what you would normally only be interested in).
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