How to return the operating system selection dialog?

Question

Windows

There are 2 disks. On one (Basic) Windows XP is installed, on the other Windows 7. When loading, a dialog for choosing the Operating System appeared. It was possible to be loaded both under that and under that. After formatting and reinstalling on the main Windows XP drive, the OS selection dialog disappeared. How to return it? So that you can boot from Win 7 again if necessary?
I know that I need to edit boot.ini, but what exactly should I write there ??

Answer 1

soft.oszone.net/program/9336/MultiBoot

Answer 2

link in English
No need to edit anything.
You don’t need to boot from 7, you need to restore the bootloader using the windows 7 installation disk from under windows XP

Answer 3

Use a very simple and convenient EasyBCD program , it checks the partitions for the presence of an OS and allows you to add them to the list of bootable OSes through the bootloader.
You can download it from the link soft.oszone.net/download/4063/EasyBCD.html