What is Hard disk ?

                   Hard disk

·       Hard disk is a rigid non-removable magnetic disk with a large data storage capacity.

·        The hard drive is the computer's main storage media device that permanently stores all data on the computer.

·        The hard drive was first introduced on September 13, 1956 and consists of one or more hard drive platters inside of air sealed casing.

·        Most computer hard drives are in an internal drive bay at the front of the computer and connect to the motherboard using either ata, scsi, or a sata cable and power cable.

Types of Hard disk

    1.      IDE (Integrated Device Electronic) or ATA (advance technology attachment).

   2.     SATA (serial advanced technology attachment).  

   3.     SCSI (small computer system interface).

   4.     External Hard Drive.

1.    IDE (Integrated Device Electronic) or  ATA (Advance Technology Attachment) :

·        IDE is a standard electronic interface used between a computer motherboard's data paths or bus and the computer's disk storage devices.

·        The IDE interface is based on the IBM PC Industry Standard Architecture (ISA) 16-bit bus standard, but it is also used in computers that use other bus standards.

·        Most computers which are sold recently, uses an enhanced version of IDE called Enhanced Integrated Drive Electronics (EIDE).

·        We can connect maximum two hard disk to a single controller, or one hard disk and one DVD Drive to a single controller.

·        Speed of IDE hard disk is 100 MB per second.

·        We have to perform Jumper Setting on Hard disk or IDE Optical Drive for connecting two or more Hard disk or Optical Drive.

IDE HARD DISK

MASTER SLAVE SETTING

   Setting as a Master:

·       Use this setting if you are installing an additional hard disk drive to a single IDE cable with a hard disk drive Set as Slave, jumper one hard disk drive to Set as Master, and the other to set as Slave.

·       Use this setting if you are installing an additional hard disk drive to a single IDE cable and the Cable Select setting is not recognized.

   Set as Slave:

·       Use this setting if you are installing an additional hard disk drive to a single IDE cable with a hard disk drive Set as Master, jumper one hard disk drive to Set as Master, and the other to set as Slave.

·       Use this setting if you are installing an additional hard disk drive to a single IDE cable and the Cable Select setting is not recognized.

   Cable Select:

·       This setting is the default setting for pata / ide hard disk drives.

·        With the Cable Select jumper setting, the BIOS determines whether a hard disk drive is Set as Master or Set as Slave by its position on the IDE cable.

·       If the hard disk drive jumper is set to Cable Select and is connected to the black connector on the end of the IDE cable, it is recognized as Set as Master for that pata controller.

·       If the hard disk drive jumper is set to Cable Select and is connected to the grey connector on the middle of the IDE cable, it is recognized as Set as Slave for that pata controller.

Note: When using Cable Select, your system must meet the following conditions:

·       Your systems host controller must support Cable Select.

·       Your hard drives must support Cable Select.

·       Your cable must support Cable Select.

2.   SATA (Serial Advance Technology Attachment):

·        Serial Advanced Technology Attachment, often abbreviated SATA , is a serial link - a single cable with a minimum of four wires creates a point-to-point connection between devices.

·        One of the main advantages of Serial ATA is that the thinner serial cables facilitate more efficient airflow inside a form factor and also allow for smaller chassis designs.

·        As an evolution of the older Parallel ATA physical storage interface, SATA host-adapters and devices communicate via a high-speed serial cable.

·        Several advantages over the older interface: reduced cable size and cost, native hot swapping, faster data transfer through higher signaling rates.

·        We can connect n number of sata hard disk or Optical drive depends upon the number of sata port available on the motherboard.

·        Sata data connector has 7 pins whereas Sata power connector has 15 pins.

SATA HARD DISK CONNECTIONS

·       
                                     

Standard  Data connector Pins Connections
Pins	Similar	Function
1	1st	Ground
2	2nd	A+ (transmit)
3	2nd	A- (transmit)
4	1st	Ground
5	2nd	B – (receive)
6	2nd	B + (receive)
7	1st	Ground
----	-----	Coding Notch

Standard Power Connector Pins Connections
Pins	Similar	Function
---	-----	Coding Notch
1	3rd	3.3 Volts Power
2	3rd
3	2nd	Enter/exit Power Disable (PWDIS) mode
4	1st	Ground
5	2nd
6	2nd
7	2nd	5 Volts Power
8	3rd
9	3rd
10	2nd	Ground
11	3rd	Staggered spin up/activity
12	1st	Ground
13	2nd	12 Volts Power
14	3rd
15	3rd

·      

·        Speed of Sata drive according to their version:

1.      Sata 3.2      16 Gbit/s

2.     Sata 3.0      6 Gbit/s

3.     Sata 2.0      3 gbit/s

4.     Sata 1.0      1.5 Gbit/s

3.   SCSI (Small Computer System Interface)

·        Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices.

·        SCSI is capable of supporting eight devices, or sixteen devices with Wide SCSI.

·        SCSI is a standard for parallel interfaces that transfers information at a rate of eight bits per second and faster, which is faster than the average parallel interface.

·        SCSI-2 and above supports up to seven peripheral devices, such as a hard drive, CD-ROM, and scanner, that can attach to a single SCSI port on a system's bus.

SCIS HARD DISK

4.   External Hard Disk.

·        External HDD typically connect via USB; variants using USB 2.0 and Others interface generally have slower data transfer rates when compared to internally mounted hard drives connected through SATA.

·        Plug and play drive functionality offers system compatibility and features large storage options and portable design.

·        External HDDs are usually available as pre-assembled integrated products, but may be also assembled by combining an external enclosure (with USB or other interface) with a separately purchased HDD.

·        They are available in 2.5-inch and 3.5-inch sizes; 2.5-inch variants are typically called portable external drives, while 3.5-inch variants are referred to as desktop external drives.

EXTERNAL HARD DISK

External Hard disk