Question- How to make it impossible to put in a floppy disk until after startup is done running

Ordinarily, when you put in a floppy disk with a startup program attached to it, the computer uses that program instead of the regular startup. Is it possible to either

A: make it impossible to insert a floppy disk until after startup is finished

or

B: Disable a computer from using a disc's startup program

thanks.

I think there's a tutorial about this, but I'm not sure, you can search on the forum.
You have two options:
1) Change the shell program so it doesn't load the disk's startup (I think this is what the tutorial does).
2) Put a disk drive on top of the computer with a startup file. It will be used instead of any other startup file.
The first one will work for every computer, but you can't use startup files on disks. The second one will just work on the computer you use it, and may not be usefull in some situations, since you would have to hide the disk drive so no one can change the disk.

How about:
3) Use a piston to push something in front of the drive so people can't get at it until your program retracts the piston at the right time.