Hale
I think at this point it does not really matter what the OS prefer, both mechanisms are out there in large quantities. Methods for switching translation modes have been discouraged because they encourage the end user to loose all of his data. I worked very hard to get CHS obsoleted from ATA/ATAPI-6 to help eliminate the propagation of boundary conditions. However, the piece you are concerned about is the front end of the INT 13 legacy functions. The easy solution to this problem is to stop calling them. The INT 13 extensions (BIOS EDD Standard) specify that the addresses are passed directly through to the device. So, if you want to get away from translation, use the extensions.
-----Original Message-----
From: Hale Landis [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, July 11, 2001 9:45 AM
To: [EMAIL PROTECTED]
Subject: [temp t13] Re: BIOS Large or LBA setting?
** This is the quasi-official and semi-temporary T13 email list server. **
>Curtis Stevens <[EMAIL PROTECTED]> said:
>I do not understand the BIOS "Large" or "LBA CHS Translation".
>Cab you be more specific? The BIOSes I worked with in a former
>life did not have an option to enable the 4x functions and they
>were not dependent on drive size. As far as I know, the process
>remains automatic...
Large and LBA have been used to describe the two different
methods of doing CHS translation for drives >528MB and <8GB. I
think Phoenix always used or defaulted to Large. Large is the
method that was orginially used on ESDI drives when those drives
exceeded 528MB (before the time of ATA). The LBA method has been
used by SCSI adapters to emulate CHS. But in the early days of
LBA capable ATA drives, Western Digital promoted the LBA scheme.
The result was that many BIOS supported both schemes and made a
human select the one to be used by the BIOS. Large is generally
faster because it uses some simple bit shifting while LBA uses
32-bit multiple and divide.
I think the real question here is this: Do the OS folks have a
preference? I know that that an OS driver must perform a bunch
of tests (reading various CHS locations and watching the BIOS to
see what real CHS or LBA is sent to the device) to determine
which CHS translation scheme is being used.
*** Hale Landis *** [EMAIL PROTECTED] ***
*** Niwot, CO USA *** www.ata-atapi.com ***
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