ERU backs up your Windows Registry, your INI and startup files to a location of your choice, so that even if something happens to your computer (such as a corruption of your registry from adding invalid hardware, or deleting the wrong thing from the device manager) it can be recovered without actually having to be able to boot windows (which may not be possible).
You do not need to do anything in DOS with ERU unless there is a problem. But before it comes to that, you have to prepare.
Find your ERU.exe file and execute it. This window should appear: Click NEXT.
This selects where you will backup your system files to. You have to MANUALLY CHANGE THIS to "Other Directory". Since the files you are backing up are very large, a single floppy will not hold them all anyway I recommend you back them up to your C: drive. It may sound stupid at first to back up your system files to the drive that may be damaged, but how much sense does it make to backup system files to a floppy should your system completely crash? The files will be essentially useless to you because the OTHER FILES (user documents and applications) that the backup refers to are most probably destroyed or not on whatever other system you may choose to restore it to.
Select the local directory. If you make many changes to your system you will need more than one backup. I recommend making several throughout the process of first installing the Operating System to a computer (like one the FIRST TIME you're able to boot it, and one after all your hardware is correctly identified, one more after all your software is installed). I usually name them after the date that I do the backup. I put them all into C:\ERD just to organize them.
This is basically a confirmation dialog for which files you'd like to backup. These are the more general system files. It is possible to add files to this by editing a text file that configures how ERU works, but for our purposes, you really need to just click NEXT here.
Watch the progress meter. It'll stop when it's done. It may take anywhere from about 5 seconds on a P3-500 to a minute on a 486-66 (I know from experience).
All done Click OK. You have successfully backed up your system files.
And that's all...
It's backed up up now to the directory you chose in Step 3. You can forget about it until there is a problem.
If there's a problem - that you can not get into windows - then you need to restore the backup. This is done in DOS.
Boot up with a bootable floppy.
CD to the directory which you had backed things up to.
Run the recovery app (ERD.EXE)
You have to click "RESTORE" and then "OK", but I can't get those images so you'll have to do that on your own.
Windows will be fixed to the state it was when you backed up (which may not be perfect, but at least you know it worked).
Good luck,
Shawn K. Hall