The limitation is due to the IDE controller and the UTV's BIOS.
This is a common finding in the PC world, and new 48-bit addressing IDE controllers are becoming available, moving the 137GB limit up to 4TB.
The limitation is entirely in the BIOS.
One of the specifications of LBA48 is that it must be 100% backward compatible with LBA28, therefore almost any IDE controller can support it.
The BIOS could be rewritten to support larger drives, but I don't know of anyone working on this and I doubt that it will ever be done.
LBA backward compatibility makes sense, but how does an LBA28 controller address the space beyond 137GB if it doesn't have the firmware and/or hardware to do so?
Or are you saying that all current controllers support LBA48?
I'm not an expert in this area, so I may not be 100% correct here, but as far as I understand it is this:
The original ATA spec used what was called an Int13h interface. If you are familiar with older computers, you may remember that to configure a hard drive you needed to specify the specific head, cylinder and sector addresses in the BIOS in order to access the BIOS. The problem with this interface was that it was only 24bits and that it couldn't address anything higher than 8.4gb.
To break the 8.4gb barrier, all ATA controllers now use a new interface that supports 64-bit Int3h extensions. Basically, what this means AFAIK is that all ATA controllers that support hard drives that are larger than 8GB are physically capable of addressing up to 64 bits - or 9.4 trillion GB. The head, cylinder and sector information are translated through Logical Block Addressing (LBA).
LBA is just a method of translating the disk information from the disk controller to the BIOS. The BIOS then translates the information back to the OS. The BIOS in an Ultimate TV only supports LBA-24 geometry translation. If it were updated to support LBA-48 then an Ultimate TV would be able to support hard drives that were 4 terabytes in size!
Like I said earlier though, I don't know of anyone actively working on modifying the UTV BIOS, much less if it's even possible to reflash it with a new one!
Last edited by Flagg; 10-26-2003 at 01:33 AM.
Just for the record, an LBA48 patch has been done with the Xbox, thus breaking the 137GB limit.
Hey NghtShd, nice to see you here!
Any input you have would be greatly appreciated.
FYI for anyone else reading this thread, NghtShd is one of the premiere BIOS modders in the XBOX world - and the developer of the XBOX BIOS patch tool - XBTOOL.
If anyone could give a truely informed opinion on this matter, it would be him.
Last edited by Flagg; 10-28-2003 at 06:25 PM.
I'm sure there are many people here much more knowledgable than I, but I did want to note the success with the Xbox. It gives some cause for hope.