Installed under the dos not know unless you ask DOS 7.1 disk, can be downloaded from this site.
I downloaded from this site DOS 7.1, then my laptop hard drive installed on the desktop as the primary. Then, I started in the DOS CD drive of the computer. Through the installation of the part, it asked if I would allow the disk to write its own MBR. (I did not let this writing.) Process when I turn off the computer, drive in my laptop, and it has a direct and failures, invalid system disk. I can not think what else to do.