Re: What is an Invalid Media Descriptor mean in relation to hard disks

The Media Descriptor on a MS-DOS formatted disk is a single byte which has a code describing the type of disk. This Media Descriptor is used by the computer's operating system to decide how to access the contents of the disk. The Media Descriptor is the 16th byte in the boot sector of the disk.

There are 9 Media Descriptor codes defined in my reference manual, 0xF0 and 0xF8 through 0xFF. The Media Descriptor for a hard drive is 0xF8.

When your hard drive "crashed", some information stored on the disk was corrupted. Tools like scandisk, that check the disk for logical consistency, first look to see that the Media Descriptor is one of the allowed types and that the type makes sense for the drive. In your case, the Media Descriptor is almost certainly not 0xF8 like it should be.

Unfortunately, you can't just change the Media Descriptor and have everything be fine. Most likely, more than just the one byte on your disk was corrupted, and the Media Descriptor is just a symptom. In order to really repair your filesystem, I suggest that you look into disk utility programs. If you need some information about such tools, a good place to start would be Yahoo's system utilities reviews

In case you were wondering, the notation "0xF8" is a semi-standard way to write hexadecimal numbers. Thus, "0xF8" means "the number F8 in base 16" and is equivalent to 248 our usual number system of base 10.