virtual floppy虚拟软驱，那么就只能加载标准软盘格式的img（720K，1.44M，2.88M）

使用方法用vfd help命令查看。

Virtual FD version 1.0

Usage:
VFD command [options]

Commands:
INSTALL [driver path] [/AUTO]
Installs the Virtual FD driver.
REMOVE Uninstalls the Virtual FD driver.
START Starts the Virtual FD driver.
STOP Stops the Virtual FD driver.
MOUNT [image file] [/L:drive letter] [/RO | /720 | /144 | /288
Mounts a floppy image to the virtual drive.
UMOUNT Unmounts the currently mounted floppy image.
STAT Displays the current driver status.
HELP [command]
Displays the VFD usage help.

All commands and options are case insensitive.
Administrator rights are required for install/remove commands.
Power User rights are required for start/stop commands.
Other operations can be performed by a regular User.