I know the question is a little out of the ordinary, but it is for testing purposes. So is is possible to simulate, or much better yet, create bad sectors on a hard drive? Like a low level erase of part of the disk? I am pretty sure it was possible on floppy disks, just wondering if there was a way to do it on a hard drive. Again, this is just for testing purposes, and would be done on an old drive that is not cared about.

Assuming you're referring to (S)ATA... Not all (S)ATA disks support the related commands, but the typical answer is "yes" - depending on exactly what distinction you are making between simulate and create. Note that delibrately created bad sectors (sometimes called "soft bad") are not treated in exactly the same way by modern disks, as "real" bad sectors - hence why some people might call that simulation and not creation. However they do cause a UNC when they are read from, like a "real" bad sector would do.

Look at MHDD (from memory, the command is "makebad"), unless you're planning on writing your own software to do this.

Thanks! That appears to be exactly what I was looking for. And it works on the drive I want it to (works so well I am writing 0's to the drive as I type this to get it back to life).

You're welcome - I'm glad that works for you