Couldn't you do this with either Grub or maybe the XP boot manager installed on HDD1's MBR?

Is possible ~ probably 'smart boot manager' is a good choice here (no linux, OS independent) .. https://www.thefreecountry.com/utilities/mult … -managers.shtml

I'd look at LILO or GRUB, but I'm a Linux dork. IIRC, installing Windows versions in the right order and it would find the other MS OSes and set up the boot.ini appropriately. DOS/98, then the NT products, likely with the most recent installed last.

In a way you already have a suitable boot loader, either the XP or 2k one. BACKUP!!! Then hack at boot.ini, after reading the fine manual, which will be documented a million times out there.

Insanely, an XP machine here I network boot. It has XP and Debian locally installed, but to be able to change the default boot OS remotely I effectively moved the bootloader config onto the network. The PXE config, like GRUB or LILO (or syslinux), can chain-load to any partition on any local disk, I think.

Looking into the boot.ini is perhaps best to start with, though.

I've done it with XFDISK which does this by hiding partitions

I do : DOS, NT4, Win95 with "smart boot manager"
It install in the MBR from DOS and it is fully configurable while you are running it (unlike grub). And also relatively easy to use.
Once you are on smart boot manager, you do something like CTRL-H to detect partitions, then you will be able to move them and rename them to what you want in the boot menu and save everything.

I also just looked at XFDISK, It seam to be a good choice too, especially if it can be configured from the boot ui like the smart one.

there was a program called vcomm system commander that let you do that

https://www.youtube.com/watch?v=8x2r2bZmN7o

Plop boot manager may be an option. https://www.plop.at/en/bootmanager/intro.html

I did something like quad boot, years back. Using Os2 boot manager, wich are the simple version of EXBM.

What I remember, is that some operating systems can only boot from primaery partitions, were as others can boot both extended as well.

I also remember that old ATA/IDE drives will only accept up to 4 primaery partitions, and if my memmory serves correct, then three primaery and one logic. However the bootmanager need one primaery as it is not a bootsector tool.

Then some operating system can actually boot from a primaery partition on a slave drive. So you are not far off in this regard. However some operating systems will set the install partition as active, instead of the boot manager, during installation of those operating systems. But it is just a matter of doing a fresh install of the boot manager, once all operating systems are installed.

My point is. Test installation of all operating systems, in regards to what type of partition and what drive (master/slave) they can install to and boit from. Then figure out in what ordet you need to install them, and then finish off by reinstalling the boot manager. Alternatively reinstall it after each installation test run, to see if booting through bootmanager is possible.

Happy tinkering.

Pretty sure you can do it automatically by:
1) creating 3 primary partitions
2) installing dos and then 9x on the first partition
3) installing 2k on the second
4) installing xp on the 3rd

I'm unsure if dos will show by default in the resulting menu, but it should be accessible by f8 after you select 9x

I base this on doing it many many years ago.

Pretty sure DOS 6.22 on first partition will become DOS 7.x when you put Win98 on top of it.
Since there is DOS mode build-in for Win98, I wouldn't consider it a seperate OS system (it's DOS7 is Win98, but without pretty GUI on top). So you drop from 4 systems to three by doing that.

It's probably possible, below is from my PIII using Boot-US as you have found. I like it because it allows me to hide the partitions from the other operating systems.

It can be an difficult to get working however, with a lot of testing what OS will overwrite the mbr or fail to boot properly. NT4 was an utter pain for ending up with a flashing cursor instead of loading properly. I had no major issues with freedos, 98 or 2000 though. Boot-US has a Windows application that installs the mbr loader and configures the menus.

You could install all OS with only one disk installed at a time, then create the mbr afterwards. Sometimes I would also use plop boot loader to trigger a one time boot to a partition to allow mbr recreation when it had been damaged by an OS install.