How to make a choice of operating systems at boot?

Question

linux

There are two hard drives, on one Windows, on the second linux. Each one was installed by disabling all extraneous hard drives, so now there is no choice which one to load at computer startup. You can switch from one to another only by changing the primary hard drive in the BIOS. It is not comfortable.
Actually, the question is, is it possible from the current situation, by installing some kind of mini-fostin, to add a choice at boot, which OS to boot?

Answer 1

set the screw with Linux first in the BIOS
with the second screw connected, with Windows, update grub sudo update-grub
it will see the second screw and create a line in the menu to start Windows

Answer 2

In Linux, for any reason, some kind of bootloader is already used (most likely grub), you can configure it so that it also loads Windows.