Can I simulate a boot disk to achieve this?
 

I am using redhat 9, grub is on mbr, has a boot partition.

Can I boot from a simulate foppy disk before grub is loaded?

What is a "simulate floppy disk?" If you bios is set to boot floppy first in the sequence, you can boot from a bootable floppy before the hard disk, which is where the grub bootloader is located.

Thank you.

Assume that, my bios is set to boot floppy first in the sequence, at the booting time, in fact, there is no floppy disk in the floppy device, however, the machine would consider there is a floppy disk (I call it a simulate flopp disk), and I could config what files in the harddisk would be considered as the files in the simulate floppy disk by the machine. Could I achieve this?
Thank you.

By the way, nice to meet you, Chinese friend.
Very glad, just see your location is China too.

Probably missuderstanding but it would be easier to just put an alternative menu in grub's menu.lst and choose that on startup. Perhaps change runlevel 4 and boot into that.

Thank you. Can I boot from a simulate foppy disk before grub is loaded?

If there is no floppy in the disk-drive, the computer will go on with the next boot item, likely the harddisk, or cd-rom, or whatever you've setup.

As far as I know there is no such thing as a simulated floppy disk. You can mount an image of a floppy disk, but I don't think thats what you mean.

Maybe it would be easier If you told why you want this simulated floppy, or where you are going to use it for..

Thank you. And sorry, the word "loading" should be "loaded", I have edited it.

I want this simulated floppy because sometimes the real floppy disk has bad sectors, the second reason is I want check it is a right rule or not.

I think in some cases, for example, grub cann't be used, mbr is not very good, the floppy disk is useful.

allright, an image from a floppy on your harddisk doesn't get bad sectors as fast as a floppy dos, so thats correct.

OK, when your MBR is damaged, you use a floppy. But to use a simulated floppy, that is, to boot a floppy image form your harddisk, you will also need your MBR on the harddisk, so in that case a simulated floppy disk wont do you any good.

well, I guess not.

Yes, I am in Kunming. They have answered your questions, I believe. Perhaps it would be best to have a floppy sometimes. If you are concerned about the data on the floppy being damaged, you could burn a boot image to a CD that would boot before grub. That would be okay if the floppy was bad. I use a bootable Win98 disk a lot of times working on Windoze computers.

How to boot from a simulate floppy disk after grub is loaded?

For example, there is another grub in the simulate floppy disk, or there is an operating system's installation booting files.

I do not understand this question. Is there some reason you do not want to boot with grub?

I want to install freedos and freedos32 on the harddisk's logical partition.

On the other hand, some operating system's installation need boot from floppy disk, but I prefer booting from harddisk.

Sorry that I cannot help you. Wo bu zhi dao freedos. I do not know of any operating system that NEEDS to boot from a floppy. Also, there is a lot I do not know. I hope you can get what you want. For me, what I want is not to ever boot any Micro$loth operating system for the rest of my life.

freedos and freedos32 is under GPL.

Yes, few operaing system must boot from floppy disk, in most case, it just is a choice.