A FEW????

Damn near every one on the Planet has Master/Slave Jumpers.

Drives are not DETECTED by DOS, they are Detected by the BIOS.

A drive jumpered as Master, IF repeat IF the Master and Single/Standalone settings are different, WILL NOT BOOT if the Slave is removed.

Some drives Master and Single are the same jumper, some it is different. There is usually a little diagram, note the key pin, the diagram is usually upside down.

If you do not know how or do not feel comfortable changing this, this is a job you should not be attempting to do. Changing the jumper is quite easy, and poses no danger whatsoever.