BOOT.INI
From BetaArchive Wiki
Boot.ini is the Windows Boot Configuration file, called by NTLDR. It is surpassed by the Windows Boot Configuration Data Store in Windows Vista and later.
Example
An example of a boot.ini file:
[boot loader] timeout=30 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
If the boot loader timeout option in boot.ini is set to 0, the NTLDR boot menu does not appear, and insted defaults to the first OS listed.