What's the purpose of the pins besides the SATA connector in a hard drive 3.5"?

[Rodion15]

In 2010 and 2011 iMac hard drives, this pins were a temperature sensor that is connected to the motherboard. I wonder what's the purpose in other non-Apple hard drives. I never saw these in 2.5" hard drives.

 

[drtweak]

They are used for the HD Temp and also to limit compability for older PC's that only support 1.5Gbps. Its like back in the day with the 37GB hard drive limit. old 40/80 GB PATA drives had a jumper to limit them to 37GB to work on older machines.

there are other items as well but for the most part they are never used.