I wanted to try Windows 8 so I downloaded the x64 preview.
I wanted my Window 7 system to be unaffected so I removed power from that disk and added a new disk to my system.
I installed Windows 8. That went ok except that once the mouse was unavailable during the later setup but later became operational at the next boot. I reinstalled again and the issue did not occur.
I wanted to copy some data from my Windows 7 disk so I restarted with that disk powered on. I moved over the data.
I wanted to verify I could boot windows 7 -- I could not. I restarted with the Windows 8 disk unpowered and could still not boot windows 7! I booted the windows 7 install disk and went to repair -- It noticed that startup needed to be fixed.
It did so and now I was able to boot windows 7.
Then I restarted with the windows 8 disk powered on and it would not boot. I restarted with the windows 7 disk unpowered and the windows 8 disk would not boot. I booted the windows 8 install disk and chose repair but it did not diagnose
or fix the startup issue.
Eventually I found that bcdboot fixed the problem.
I know there is a boot manager and you can have a menu to select different operating systems to boot and I grant that I don't know how the boot manager works but there are two basic problems. If I have two separate physical disks, each with a complete
setup including boot managers -- why cant I use the bios to select which physical disk to boot with its boot manager? Number 2, why does windows insist on doing something to the disks (or is it the bios?) that prevents one of them from booting?
Why did it do that without asking me or notifying me?
I have a new UEFI system installed with disks cleaned of any old partitions. Windows install, I think, is able to use the newer partitioning system. Even so, it seems unable to handle the aforementioned situation.
Once, when I had both disks powered on, I went to a install disk repair -> command prompt and bcdedit said that it could not show me anything because of an ambiguous situation. Is it because bcd data uses drive letters?
Also, sometimes, the Windows 8 install disk -> repair menus cause an unexpected power off.