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Booting another Windows on the same machine

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#1 xpt


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Posted 15 June 2020 - 12:41 PM



Last time I check, having more than one Windows on the same machine is possible but booting them needs quite a struggle, you need to carefully hide whatever other windows partitions that comes before it using g4dos. 


Has the situation been improved? 

Can booting another Windows on the same machine be simpler (e.g. no need hiding) now? 

Can Syslinux be used to chain-boot them?

Do the Windows still need to be in the primary partitions; can they lives in a extended partitions now?



#2 xpt


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Posted 15 June 2020 - 12:47 PM

Ops, I should have searched, 


How To Geek has a nice tutorial about setting up dual boot with multiple copies of Windows, and a good explanation of dual-booting in general.


#3 xpt


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Posted 15 June 2020 - 12:54 PM

None of the articles mentioned if the Windows still need to be in the primary partitions. I guess it is, right? 

#4 Wonko the Sane

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Posted 15 June 2020 - 01:05 PM

Only for the record, since NT 3.1, ALL NT systems were designed to be installed on logical volumes inside extended partition.


I.e. since 1993/1994, you only need a small partiton. Primary, Active

with filesystem FAT16 if you want to boot DOS up to 6.22 (and conversely Windows 3.x)
with filesysystem FAT32 if you want to boot DOS 7.1 up (and conversely Windows 9x/Me)


This small, active, primary partition will hold also the NT bootmanager(s), i.e.:
NTLDR, NTDETECT.COM and BOOT.INI for Windows NT up to XP
BOOTMBR and \boot\BCD for Windows NT from Vista up

And any number of logical volumes, in each one you can install a different NT version[1].


The hiding has never been *needed* unless you wanted (for *whatever* reasons the OS drive letter to be C: on different OS's).


Now go back in time and read:



Then read:






Then come back here and ask your questions (if any) :)





[1] actually you can install also Windows 9x/Me on a logical volume inside extended (keeping the DOS files on the small primary, active partition), but it is a relatively long and complex procedure

  • Olof Lagerkvist and xpt like this

#5 Rootman


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Posted 17 June 2020 - 11:27 AM

Another possibility is to boot the second Windows OS from a .VHD file.  On a lark I setup a VirtualBox Windows 10 OS and then booted it from the host by using the VHD as a disk.  It works fine,


It WILL screw with the Windows activation, so if you want to keep it on Virtualbox too and switch back and forth eventually it will not activate.  I happen to be on a corporate system and have Windows 10 Enterprise so I can activate it in both places without issue. If you keep it for the dual boot on the host exclusively just activate it there. 

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