How can I read a huge hard drive? (120Gig)
BIOS calls won't work...
Using ports doesn't work... (I think)
Do I have to use a "manufacturer's specified" way? (such as reading a different port, etc.)
Also, how can I partition drives bigger than the LBA field allows? The LBA only allows for 4 Gig.
Can a MBR load a partition that is somewhere above 4Gig?
If so, how?
Reading big Hard Drives?
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Unspoken_Magi
Re:Reading big Hard Drives?
Anyone? I really need this soon, its holding me up. I don't want to use a cheap hack for the MBR anymore...
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Tim
Re:Reading big Hard Drives?
Program the IDE controller directly. Forget the BIOS.
If you're talking about your MBR code, put in a disclaimer that says, "we don't support booting from partitions beyond xxx MB".
If you're talking about your MBR code, put in a disclaimer that says, "we don't support booting from partitions beyond xxx MB".
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Unspoken_Magi
Re:Reading big Hard Drives?
Yes, but how can you even HAVE partitions past 4Gb or larger than 4 Gb... The LBA fields in the MBR are dwords...Tim Robinson wrote: Program the IDE controller directly. Forget the BIOS.
If you're talking about your MBR code, put in a disclaimer that says, "we don't support booting from partitions beyond xxx MB".
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Curufir
Re:Reading big Hard Drives?
The last two fields in the partition entry in a standard MBR are offset into drive, and size of partition. Both are 4 bytes long, and measured in sectors.
This gives you a maximum partition size of 2^32 sectors, with the final partition being offset a possible 2^32 sectors into the disk.
Therefore the maximum size disk you can describe with the MBR is 4 Terabytes (Offset plus size) with a maximum partition size of 2 Terabytes (Assuming 512 byte sectors). I you happen to possess a 4 terabyte drive then hire someone else to write your OS, apparently you're rich enough ;D.
Int 13h uses CHS so it hits a limit which means communicating directly through the IDE ports to load sectors beyond the so called BIOS limit as Tim has already suggested.
This gives you a maximum partition size of 2^32 sectors, with the final partition being offset a possible 2^32 sectors into the disk.
Therefore the maximum size disk you can describe with the MBR is 4 Terabytes (Offset plus size) with a maximum partition size of 2 Terabytes (Assuming 512 byte sectors). I you happen to possess a 4 terabyte drive then hire someone else to write your OS, apparently you're rich enough ;D.
Int 13h uses CHS so it hits a limit which means communicating directly through the IDE ports to load sectors beyond the so called BIOS limit as Tim has already suggested.