The builds are full installations. It has always been, that, when installing an OS, it takes boot precedence.

davehc said:

The builds are full installations. It has always been, that, when installing an OS, it takes boot precedence.

This is more than simply taking precedence. It appears to rewrite something in the bootloader, such that the option to boot to another OS is no longer there! Without unplugging the Win10 SSD I wasn't even given a choice, the thing would simply boot to Win10 no matter what I did.

So System/ Advanced system settings/ Advanced/ Startup and recovery/ Settings did not show another os ?
That kind of wrenched my last dual boot I didn't think to look in this area :/
Attachment 7430

removed my comment, it was already posted about EasyBCD

but this link the direct site to NeoSmart the makers

http://neosmart.net/EasyBCD/

Windows 10 has more advanced security, and as such it replaces the boot loader with a new version that supports the new security.

Windows has always basically blown away the boot loader when you loaded the OS. Ask users of Linux, and other OS's.. Microsoft's position is.. you're installing this OS, they need to make sure it boots and runs correctly. You're free to change it after the fact, but they're going to make sure everything is defaulted after install.

Only when you install Windows to a second disk (ie, your installing to a disk that is not your boot disk) has Windows ever kept the existing boot configuration.

Yep an irritating trait it also reset to 0 seconds too just to irritate a person
Essentially the setting is useless,
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Mystere said:

Windows 10 has more advanced security, and as such it replaces the boot loader with a new version that supports the new security.

Windows has always basically blown away the boot loader when you loaded the OS. Ask users of Linux, and other OS's.. Microsoft's position is.. you're installing this OS, they need to make sure it boots and runs correctly. You're free to change it after the fact, but they're going to make sure everything is defaulted after install.

Only when you install Windows to a second disk (ie, your installing to a disk that is not your boot disk) has Windows ever kept the existing boot configuration.

I am installing it on a separate disk. I just haven't realized that "upgrading" to the new build behaves similarly to a new install. And so while upgrading I did not unplug all other drives. What the upgrade did, was to change the bootloader *on another drive*, setting Win10 as a default OS and getting rid of the time delay, such that no choice of the OS was visible. As a result, I could not boot to Windows 7 anymore.

Previously, I had Windows 8 installed on that separate disk and I never run into that problem.

Run into that myself, SSD is first boot device with W 8.1 on it, Separate HDD for W 10TP is what it was when 9841 was installed. Boot menu was installed on both of them. So, I booted of that boot menu from HDD and after updating TP to 9860 only that installation was available so it must have changed something on that SSD and it had business doing that, should have done it on HDD only. I was able to get boot menu back but this I didn't expect from just an update otherwise I would have disconnected other drives while doing it.