HARD DISK DRIVE

What is a hard disk?

A hard disk drive (HDD) is a device for storing and retrieving digital information, primarily computer data. Hard disk drives have been the dominant device for secondary storage of data in general purpose computers since the early 1960s. They have maintained this position because advances in their recording capacity, cost, reliability, and speed have kept pace with the requirements for secondary storage. The capacity of hard disk drives is given by manufacturers in megabytes (1 MB = 1,000,000 bytes), gigabytes (1 GB = 1,000,000,000 bytes) or terabytes (1 TB = 1,000,000,000,000 bytes).

These hard disk drives are available in different sizes. The hard disk drives we use today in desktops are 3 and half inches big and those had disk drives used in laptops are 2 and half inches big. Before these hard disk drives 5.25 inches hard disk drives were in use and in even before times 20 inches hard disk drives were used which were in the size of our school benches.

The hard disks are of two types

1)      IDE (integrated drive electronic)

2)      SATA (serial advanced data attachment)

Though the hard disks are of different types they very only in their connectors and all the remaining components are the same.

Components of a hard disk:

1)      Platter

2)      Spindle motor

3)      Head

4)      Head actuator motor

5)      Data cache

6)      Logic board

7)      Connectors

  Platter:

This platter is simply a disk made up an alloy of aluminum and some magnetic material.  The data of a computer is stored in the platter. In a platter the data is stored in tracks and sectors. Here tracks are the circles that are around the centre and sectors are a part of these tracks. The data in the platter is stored in zigzag manner. This type of storage is called master boot records. The data is always filled from inner edge to outer edge.

                                                   The metal disk in the image is the platter

Spindle motor:

This motor is place under the platter. Its purpose is to rotate the platter. A spindle motor generally has rpm of 3500/4500/5400/7200/10000/12000/15000. The latest hard disk drives have a spindle motor of highest rpm.

Head:

It is a small nail like pin. It is used to read and write data from the platter of a hard disk drive. The head can access every surface of a hard disk with the help of spindle motor and head actuator motor.

                                        
Head actuator motor:

It is connected to the head with an arm. The function of the head actuator motor is to move the head from inner edge to outer edge of the platter of a hard disk drive.

Connectors:

As I have told u before these connectors are of two types:

1)      IDE(integrated drive electronic)

2)      SATA(serial advanced technology attachment)  

                                                                      IDE Connectors

These types of connectors have 3 compartments in the hard disk and they are:

1)      Data transfer

2)      Jumper section

3)      Power port

   

Power port:-

The hard disk requires some electrical power to run the platter, spindle motor and the head actuator motor. This power is supplied to the hard disk by the SMPS after filtering the given supply of 230volts to the required amount of power. This port consists of 4 bold pins.

Data transfer:-

The data in the hard disk is accessed by the CPU through the data transfer port given to the hard disk drive. This port is connected to the mother board directly by an IDE data cable. This port consists of 39-40 delicate pins in two rows.

Jumper section:-

This section of port in a hard disk is used when we use a single IDE cable to connect two hard disks to a motherboard.  This port consists of 6 or 8 delicate pins in it in 3 rows and 3 or 4 columns. Jumper is a small clip type thing that is used to join any two ports in same column but we should not join the pins in the same row. When we add two hard disk drives to a single IDE slot in mother board we connect two hard disks to the connector above the pins which have short length between them are connected to hard disk drives and the third one is connected to the motherboard. The hard disk connected to the top port is called master and the second one is called the slave. These master and slave are mentioned to the computer using the jumper. The position of jumper to mention master and slave are given in the images below.

                                                                           SATA connectors

These types of connectors have 2 compartments in the hard disk and they are:

1)      Data transfer

2)      Power port

   

Data transfer:-

The data in the hard disk is accessed by the CPU through the data transfer port given to the hard disk drive. This port is connected to the mother board directly by an SATA data cable. This port consists of 7 golden strips in a single row like the strips in an USB port.

 Power port:-

The hard disk requires some electrical power to run the platter, spindle motor and the head actuator motor. This power is supplied to the hard disk by the SMPS after filtering the given supply of 230volts to the required amount of power. This port consists of 15 golden strips like the strips in data transfer port. If the SMPS used has an IDE power cable we can use an IDE to SATA converter power cable

Note: - there is no jumper section in the SATA hard disks because we can connect only one hard disk in

             SATA cable.