Quote Originally Posted by PedroPalhoto View Post
Example: DOS, Windows 98 SE, Windows XP and Windows 7 on one hard drive, besides multiple Linux instances.
ATTENTION: not tested yet (awaiting peer warnings before wasting more hours on this than necessary).

To clear up, I'll leave an example of what I believe (at the moment) could be achieved to max out this combined approach. Has anyone tried anything similar?

Grub entries:
1. FreeDOS 1.1 + Windows 3.1; Windows XP; Windows 7 [More Win2k to Win8 instances could be installed/accessed from this entry]
2. MS-DOS 6.22 + Windows 98 SE
3. Some other OS or combination of OSes that requires a primary partition.
4 to 60: Other OSes that can boot up from logical partitions

FreeDOS and Windows 3.1 would be installed together on the first primary partition. MS-DOS 6.22 and Windows 98 would be installed together on the second primary partition.

By hiding the second partition from the first and vice-versa, the respective hidden Windows(es) could not see their counterpart primary partition while operating. With this approach I'd probably reduce each system partition's size from the suggestions saikee gave in another thread, and have a shared FAT32 logical 'Apps' partition. The 'Apps' partition would have a "Program Files" folder for each system's managed installed applications (i.e. '\Progs98', '\ProgsXP', '\Progs7'). This partition should be created before any Win2K to Win8 system partitions. To avoid wasting additional disk space with application redundancy, there could also be a common folder for as many portable apps that would work interchangeably on any Win32 OS, such as '\AppsW32'. FreeDOS and MS-DOS 6.22 could share portable applications and data on a shared logical partition below the 8GB limit.

Here's the drive lettering sequence I predict, from each boot.

FreeDOS, Win3.1, WinXP and Win7 view:
C: - FreeDOS (with Grub, NTLDR and bootmgr bootloaders) [1st primary partition]
D: - Small (~1GB) shared Data partition below the 8GB limit (MS-DOS limitation) [can be a logical partition]
E: - Common Apps partition [FAT32, logical]
F: - Windows XP system partition [NTFS, logical]
G: - Windows 7 system partition [NTFS, logical]

MS-DOS 6.22 view:
C: - MS-DOS 6.22 + Windows 98 SE [2nd primary partition]
D: - Small (~1GB) shared Data partition

Windows 98 SE view:
C: - MS-DOS 6.22 + Windows 98 SE
D: - Small (~1GB) shared Data partition
E: - Shared Apps partition
[the NTFS from F: onwards should also be available to Windows 98 if a third party NTFS driver is used]

Partition Table Example Scheme (grub/linux view):
1. 1GB FAT16/32 FreeDOS (with Grub, NTLDR and bootmgr bootloaders) [primary]
2. ~5.5GB FAT32 MS-DOS+Win98 [primary]
3. 512MB (left hidden for some other OS or combination of OSes that might require a primary partition) [primary]
4. Extended Partition [rest of the available drive space]
5. 1GB FAT16/32 Shared Data [logical]
---- 8GB Limit for MS-DOS
6. 30GB+ FAT32 Shared Apps [logical]
7. 20GB NTFS WinXP system partition [logical]
8. 30GB NTFS Win7 system partition [logical]
9 and onwards. Other Operating Systems [logical]

With this rationale, are there any alarms that go off in your mind before I spend some time testing this out?