How does grub start msdos and winpe?

I tried to use grub to start a Linux operating system without any problems, but the image and winpe used to start msdos have problems.

First, install grub on the USB flash drive in Linux.

[Code]

Mount/dev/sdb1/tmp/boot # mount the partition
Grub-install -- root-directory =/tmp/boot -- no-floppy/dev/SDB # Install grub

[/Code]

Then I tried to start the Debian installer, puppy and Gentoo, but I didn't have any major problems. Below is my grub boot menu.

[Code]

Default 0

Timeout 5

Color cyan/blue white/blue

Title Debian Installer
Root (hd0, 0)
Kernel/OS/Debian/linux root =/dev/ram0 ramdisk_size = 128000 VGA = 791
Initrd/OS/Debian/initrd.gz

Title Gentoo livecd
Root (hd0, 0)
Kernel/OS/Gentoo root =/dev/ram0 init =/linuxrc dokeymap looptype = squashfs loop =/image. squashfs cdroot VGA = 791
Initrd/OS/Gentoo. igz

Title puppy livecd
Root (hd0, 0)
Kernel/OS/puppy/vmlinuz
Initrd/OS/puppy/initrd.gz

Title msdos
Map -- MEM/OS/msdos/ghost. IMG (fd0)
Map -- hook
Chainloader (fd0) + 1
Rootnoverify (fd0)

Title winpe
Chainloader (hd0, 0)/ntldr

[/Code]