China DOS Union

I boot from the USB flash drive. The USB flash drive has DOS and WinPE systems installed, and grub4dos is started through the Autoexec.bat on the USB flash drive.
Now I want to switch to the boot menu when booting from the hard disk, and select to enter XP (there are XP and Vista systems installed on the hard disk). I want to ask if I can add an item in menu.lst to boot from the hard disk, but I don't know how to write it?
Note: I don't want to boot the XP system, just want to bring up the boot menu, and then select which system to start, because sometimes I may also enter Vista. I hope all the experts can help, thank you!

This is somewhat related to the boot mode of the USB flash drive (seeing whether the USB flash drive is booted in A drive or hard disk mode, that is, emulating a floppy disk or a hard disk). If it is emulating a floppy disk (A drive), then the first menu is adopted; if it is emulating a hard disk, it may use the first or the second menu (depending on the number and arrangement of the USB flash drive and the actual hard disk). This is only my personal understanding and the situation I encountered. Please correct me if it is wrong.

title 1. Boot from the first primary partition of the first hard disk
rootnoverify (hd0,0)
makeactive
chainloader +1

title 2. Boot from the first primary partition of the second hard disk
map (hd0) (hd1)
map (hd1) (hd0)
map --hook
rootnoverify (hd0,0)
makeactive
chainloader +1