PATA Hard Disk is a type of HDD (Hard Disk Drive). PATA stand for Parallel Advanced Technology Attachment that is a bus interface used for connecting secondary storage devices like hard disks, optical drives. 

-    It was first introduced in the year 1986 by Western Digital and Compaq

-    It uses a thick ribbon data cable.

-    It is a 40 (forty) pins connector. 

-    The data transfer speed is lower than SATA hard disk.

-    It was later replaced by SATA (Serial Advanced Technology Attachment) hard disk.

                    For examples, look PATA Hard Disk in the below picture. 

Fig: PATA Hard Disk