Difference between IDE SCSI and SATA interfaces

Characteristics	IDE	SATA	SCSI
Acronym For	(IDE) interface	Serial ATA	Small Computer System Interface
Developed in	1986	2003	developed in 1978 and publicly disclosed in 1981
Pins Used	40 Pins	7 Pins (3 grounds and 4 active data lines in two pairs)	50-pin, 68 pin, and 80-pin
Data Transfer Rate	16 MB/s originally later 33, 66, 100 and 133 MB/s	SATA 1.0–> 150 MB/s, SATA 2.0–>300 MB/s,SATA 3.0 –>600 MB/s	Ultra-640 SCSI: 640 MB/s or 5120 Mbit/s
Supported Devices per Cable	Two	One	Sixteen

Hard Disk Drive (HDD)

It is a data storage device and is made up of a thin circular discs, called "Platters", which are coated on both the sides by Magnetic Material. A Disk pack may consist of number of Platters and are mounted on a central shaft that rotates them in same direction with same speed.The Data is written or accessed in a random manner and individual blocks of data can be stored or retrieved in any order rather than just sequentially.It is connected to computer using different interfaces such as IDE, SATA or SCSI.

Information Storage: In HDD information is stored on all surfaces of platters except upper and lower surface of top and bottom platters respectively. thus,a  disk with 5 disk platters will have 8 recording surfaces. Each plotter is consist of no. of invisible concentric circles which are called tracks. A set of such corresponding tracks in all the surfaces is called cylinder. Tracks are further divided into sectors. * bit EBCDIC code is used for the information storage.The Information is stored in form of invisible magnetic spots. The Presence of magnetic spot represents binary 1 and absence represents binary 0.

The Outer tracks has greater circumference then inner tracks but each track consist of same no. of characters.Hence the data density of outer tracks is less as compare to inner tracks.