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Living Room / Re: Multibooting and Partitioning Experiments
« on: November 13, 2007, 03:15 AM »
Sorry I could only log onto this site at the home computer because the site is banned by my office network.
It is nice to talk to someone involved in the inner working of MS systems as I am not IT-related. I don't mind the discussion at all as I don't think I know that much really. That is why I always qualify myself by various statements and assumptions so that others in the know can step in if something not factual. Like you I am interested in the technical side and just able to do it isn't good enough for me.
On the MBR part I think your description is correct as the Bios program only loads the MBR and it is really the code in the MBR that utilises the 64-byte partition table between the 447 and 510th byte. I used the language loosely as though the Bios would hand over the information to the boot loader. I suppose in a way it can be correct as once the MBR has been loaded the Bios activities ceases.
On the fat16 partition it is interesting because there are Type 6 for the normal one and type e for the one that use LBA. I know the type 6 is supported in every MS system and I believe the Type e isn't but I could be wrong on this one. Can you verify by booting the last official Dos (6.22?) floppy to see if your fat16 partition, created by Win98E, can be seen by it?
You may have a better explanation as you are close to these filing systems that pen drive suppliers adopt fat16 Type 6 for all products below 4Gb and switch to fat32 if the capacity is higher. Must admit I always stick with the fat16 type 6 because that is what the Dos floppies are capable of handling.
On the VMware side my free version of an installed Linux inside a MS Windows is just a file. I can't even from one Linux see another guest Linux under the same Host. If you have done it from an boot up CD that may be something different or you have extra bits and pieces over and above the free VMware server software that I have.
In a real Linux as against a vitual machine one can access any other installed real Linux by mounting their partitions. What is more one can "change root" into another Linux thereby able to work on another Linux internally. I believe for someone like you I should describe it as using the kernel of Linux B in combination with a Bash terminal of Linux B.
The partition type is just the 5th byte in the 16-byte partition table but I don't think MS system use it publicly in the partition creation programs even though it is widely utilitised in the Unix-like systems.
Lastly I may as well learn something from you. It is concerning install a "stand alone" MS system in a logical partition.
The way I understand the MS systems is they seem to share a common MBR up to and including XP and only get changed with Vista. This is because I always restore a Win2k or xp MBR with a Dos 6.22 floppy and when it come to restore a Dos 6.22 MBR I use a XP installation CD.
I am sure there are difference but the main functionality is the same.
I read that MS MBR's function is primarily to search the 4 primaries and boots the one with the bootable flag switched on. MS MBR doesn't care what the system inside and I have used this feature to make a XP's MBR to boot up Grub (host in a dta-only primary partition as I can use XP disk management to toggle the active partition).
Now only a primary partition uses the booting flag. Although booting flag is availabe in the logical partitions but I am not aware any OS uses it. The booting flag is also pretty loose in the logical partitions because unlike in the primaries where one partition toggled on will automatically toggling the existing one off. For logical partitions we can set several of them active. Linux of course never use the booting flag.
The other aspect of logical partition is one can create 63 partitions in a Pata disk and XP and Vista has no objection of mounting them (not 100% sure with Vista but XP has no problem). Would a MS system installer be able to select any of these partitions for installation?
My puzzle is if a MS system can survive as a "stand alone" OS in a logical partition how does it boot itself? Everything about its MBR say it cannot be done.
Here is the Microsoft own web page stating the limit of fat16. I suppose if one can break this limit one can explain it too.
It is nice to talk to someone involved in the inner working of MS systems as I am not IT-related. I don't mind the discussion at all as I don't think I know that much really. That is why I always qualify myself by various statements and assumptions so that others in the know can step in if something not factual. Like you I am interested in the technical side and just able to do it isn't good enough for me.
On the MBR part I think your description is correct as the Bios program only loads the MBR and it is really the code in the MBR that utilises the 64-byte partition table between the 447 and 510th byte. I used the language loosely as though the Bios would hand over the information to the boot loader. I suppose in a way it can be correct as once the MBR has been loaded the Bios activities ceases.
On the fat16 partition it is interesting because there are Type 6 for the normal one and type e for the one that use LBA. I know the type 6 is supported in every MS system and I believe the Type e isn't but I could be wrong on this one. Can you verify by booting the last official Dos (6.22?) floppy to see if your fat16 partition, created by Win98E, can be seen by it?
You may have a better explanation as you are close to these filing systems that pen drive suppliers adopt fat16 Type 6 for all products below 4Gb and switch to fat32 if the capacity is higher. Must admit I always stick with the fat16 type 6 because that is what the Dos floppies are capable of handling.
On the VMware side my free version of an installed Linux inside a MS Windows is just a file. I can't even from one Linux see another guest Linux under the same Host. If you have done it from an boot up CD that may be something different or you have extra bits and pieces over and above the free VMware server software that I have.
In a real Linux as against a vitual machine one can access any other installed real Linux by mounting their partitions. What is more one can "change root" into another Linux thereby able to work on another Linux internally. I believe for someone like you I should describe it as using the kernel of Linux B in combination with a Bash terminal of Linux B.
The partition type is just the 5th byte in the 16-byte partition table but I don't think MS system use it publicly in the partition creation programs even though it is widely utilitised in the Unix-like systems.
Lastly I may as well learn something from you. It is concerning install a "stand alone" MS system in a logical partition.
The way I understand the MS systems is they seem to share a common MBR up to and including XP and only get changed with Vista. This is because I always restore a Win2k or xp MBR with a Dos 6.22 floppy and when it come to restore a Dos 6.22 MBR I use a XP installation CD.
I am sure there are difference but the main functionality is the same.
I read that MS MBR's function is primarily to search the 4 primaries and boots the one with the bootable flag switched on. MS MBR doesn't care what the system inside and I have used this feature to make a XP's MBR to boot up Grub (host in a dta-only primary partition as I can use XP disk management to toggle the active partition).
Now only a primary partition uses the booting flag. Although booting flag is availabe in the logical partitions but I am not aware any OS uses it. The booting flag is also pretty loose in the logical partitions because unlike in the primaries where one partition toggled on will automatically toggling the existing one off. For logical partitions we can set several of them active. Linux of course never use the booting flag.
The other aspect of logical partition is one can create 63 partitions in a Pata disk and XP and Vista has no objection of mounting them (not 100% sure with Vista but XP has no problem). Would a MS system installer be able to select any of these partitions for installation?
My puzzle is if a MS system can survive as a "stand alone" OS in a logical partition how does it boot itself? Everything about its MBR say it cannot be done.
Here is the Microsoft own web page stating the limit of fat16. I suppose if one can break this limit one can explain it too.