A hard disk drive contains rigid disk shaped platters, usually constructed of aluminum or glass which cannot be bent like floppy disc hence termed as hard disk. Since the platters cannot be removed they are sometimes called fixed disk drives.
Types of HDD :
1. IDE : Integrated Drive Electronics. IDE drives are also known as PATA drives( Parallel advance technology attachment )
· IDE/PATA Drives have usually 40 pins.
· IDE/PATA Drives offer 133 MB/sec transfer rate.
· It sends 8 bit data at a time.
· PATA Cables are used to connect PATA HDD. Two drives can be connected in a single pata cable. One as master and other as slave. The configuration of master and slave is done by different combination of jumpers in the hdd.
· SATA Drives have usually 7 pins, 4 pins in pair of two for sending and receiving data and rest 3 pins are grounded.
· SATA Drives offers generally 300MB/sec transfer rate.
· SATA Cables are used to connect SATA HDD. Only one drive can be connected in a single sata cable.
3. SCSI : Small Computer System Interface. SCSI is pronounced as scuzzy.
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· SCSI Drives have usually 50 to 68 pins.
· SCSI Drive offers generally 640MB/sec transfer rate.
· This drives are hot swappable.
· SCSI cables are used to connect SCSI HDD. Maximum of 16 drives can be connected in a single scsi cable. Each hdd have a 8 bytes hexadecimal code known as WWN (world wide name) for its identification in the cable.
4. SAS : Serial Attached SCSI (pronounced as separate letters) Short for Serial Attached SCSI, an evolution of parallel SCSI into a point-to-point serial peripheral interface in which controllers are linked directly to disk drives. SAS is a performance improvement over traditional SCSI because SAS enables multiple devices (up to 128) of different sizes and types to be connected simultaneously with thinner and longer cables; its full-duplex signal transmission supports 3.0Gb/s. In addition, SAS drives can be hot-plugged.
5. Laptop Hard disk drive.
Most modern laptops use 2.5″ hard drives. Older laptops use IDE hard drives, newer laptops use SATA hard drives. SATA and IDE drives are not interchangeable, they have absolutely different connectors.
If your laptop came with an IDE hard drive you cannot replace it with a SATA drive. The connector on your drive will not mach connector on the motherboard.
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