In addition to having certain user configurable functions, certain combinations of jumpers can configure the drive for factory test mode.
For example, Seagate's SATA jumper pins have the following functions:
- 1.5Gbps limitation jumper
- Rx (serial terminal input)
- Tx (serial terminal output)
Jumper Settings for WD SATA and EIDE Hard Drives:http://www.wdc.com/wdproducts/library/other/2579-001037.pdf