How to differentiate between SATA and PATA drives
Notebook hard drives (2.5" hard drives) are available with two kinds of interfaces: PATA (Parallel ATA) or SATA (Serial ATA). SATA drives are fairly new in the market. External dimensions for both PATA and SATA are fairly the same. The way to distinguish between the two is by looking at the connector/interface. PATA drives have two rows of pins. SATA drives have a "card edge" connector (see photo below). It's only in 2007 that we started seeing laptops/notebooks shipped with SATA hard drives as the primary drive. Prior to 2007, notebooks/laptops were shipping with PATA hard drives as primary hard drives. Make certain before you buy your hard drive what type of hard drive your laptop/notebook uses. PATA and SATA hard drives are not interchangeable.
You will also come across different naming conventions for PATA and SATA drives. Manufacturers and resellers don't refer to them as a "PATA hard drive" or a "SATA hard drive". Oftentimes, you will see them listed as "ATA-6", "ATA-7", "SATA 1.5", etc. Please refer to the chart below to get a better understanding of what type of drive you will be requiring.