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Hi,

Does anyone know where I can download the latest ata/atapi spec from?

I've read some of the tutorials on using PIO and LBA28/48 for hdd access and they've been very helpful, but to fully support and implement an hdd driver for my os I really want to know about using UDMA properly, atapi and setting the pio/udma modes for maximum transfer rates. Also how to identify/configure the devices properly and to obtain their respective geometry and feature support.

Thanks!
John

You could of at least searched around a little....

Several standards are indexed on Wikipedia.

Another useful site is http://www.ata-atapi.com/

Thanks

Did make a quick google search and all the sites I came up with wanted $$ for the downloads/specs. Will check the wiki first in future

Once you understand the methodology of LBA disk transfers, sadly, all the rest of the implementation of DMA methods is specific to PCI (with its Bus Mastering DMA protocol over the PCI bus). Unfortunately, the PCI specs cost $1500, and I have never found a free copy. Basically, it's a matter of getting the BAR (base address register) out of the PCI configuration space of the PCI disk controller, as I understand it -- but I have not implemented it myself, yet. So, you will be able to find more info on various wikis about reading PCI configurations -- but I don't think you will find the official specs.

Last ata/atapi spec you can found on site
http://www.t13.org/

Example, seach
http://www.google.ru/search?complete=1& ... 13.org&lr=

Thanks

Did make a quick google search and all the sites I came up with wanted $$ for the downloads/specs. Will check the wiki first in future

You used not right Google

Unfortunately, the PCI specs cost $1500, and I have never found a free copy.

For programming UDMA you mast have

"Programming Interface for Bus Master IDE Controller" (IDE-BusMaster.pdf)

Free copy
<link>

Uhm, the PCI spec is copyrighted and downloading it that way is illegal. Please remove the link since authorities might consider that in violation of the law.