A hard disk is a secondary and permanent data storage device that is placed in the system. It is similar to a human brain, where all the past and present events are stored. is made up of a magnetic material that helps in storing data by following the magnetic recording techniques. The latest technology has reached up to 4-terabyte (TB) of storage space, Figure 5.1 shows a hard disk drive.
1. Types of Hard Disks
The different hard disks specify the speed at which the hard disk transfers data and the reliability of the hard disk in terms of storing data. The different types of hard disk drives are :
- IDE/PATA Drives
- Serial ATA (SATA) Drives
Hard disks are of two types depending upon how it is connected to the system.
- Internal Hard Disk Drives
- External Hard Disk Drives
2. Internal Hard Disk Drives
Internal Hard Disk Drives are connected inside the system using IDE/SATA connectors available on the motherboard.
IDE (Integrated Drive Electronics) Hard Disk Drives
The IDE interface specifies that the hard disk controller is built on the motherboard These drives are also called PATA (Parallel ATA) drives as it uses parallel communication The ATA (Advanced Technology Attachment) transfers data between the hard disk and system using 16 bits bus width with speeds of upto 133MB per second. You can connec two IDE drives eg. one HDD and one CDROM drive or two HDDS to a single controlier on the system. In case of two HDDS, you must set the one hard disk to Master and other to Slave using the jumpers on the hard disk, so that the system can identify the required hard disk /This hard disk uses a 40-pin connector to connect to the system.
IDEIPATA hard disks are connected to the IDE port on the motherboard using a 40/80 pin conductor cable. Figure 5.3 shows an 80 pin conductor IDE cable.
Types of IDE Interfaces
The hard disk interface specifies the method that is used by the hard disk to send and receive data from the system using an interface/data cable. The type of the interface specifies the data transfer speed between the hard disk and the system. To use a specific interface an appropriate controller should be installed on the system and the drive should support the same.
ATA-6 is a standard approved by ANSI in 2001. It is also known as UDMA/100 or Ultra ATA/100, has a transfer rates up to 100MBytes/sec. It has with 15 bit bus width and uses a 40/80 pin conductor cable, with the additional 40 new pins being ground.
It is a standard approved by ANSI in 2004. The primary addition in ATA-7 is UDMA mode 6 that allows data transfer upto 133 MBps. It requires an 80 pin conductor cable.
SATA (Serial ATA) Hard Disk Drives
Serial ATA uses serial communication i.e. transfers data 1 bit at a time with the speed of upto 600 MB per second. SATA hard disk uses a smaller 7-wire cable to connect to the system. This cable can have a maximum length of 1 meter.
You can connect only one SATA hard disk to a SATA controller on the motherboard. This eliminates the need to set a hard disk as a master or slave. You can connect more than one hard disk by connecting them to different SATA controllers on the motherboard using separate cables.
SATA offers following advantages over IDE technology :
- Point to point connection topology ensures dedicated 600Mbytes/sec to each device.
- Thinner, longer cables for easier routing.
- Fewer interface signals require less board space and allow for simpler routing.
- Better connector design for easier installation and better device reliability.
- Hot-swap capability.
Types of SATA Hard Disk Drives
SATA hard disks are classified on the basis of its speed at which it connects to the system.
SATA 1.5 Gbit/s
It is the first generation SATA interface. It is also known as SATA 1 or SATA/150, which has a data transfer rate of 1.5 gigabits per second (Gbit/s). SATA/150 can be comparable with PATA/133 in terms of their theoretical burst-throughput. However, newer SATA devices offer enhancements such as NCQ (Native Command Queuing) to SATA’s performance 53 in a multitasking environment.
SATA 3.0 Gbit/s
The first generation SATA devices SATA/150 were scarcely faster than PATA/133 which led to the development of SATA/300. SATA/300 has increased the data transfer rate from 150 MB/s to 300 MB/s and became the fastest desktop hard disk. SATA data cable rated for 1.5 Gbit/s will currently handle second generation i.e. SATA 3.0 Gbit/s. SATA 3.0 Gbit/s is backward compatible with SATA 1.5 Gbit/s. Native Command Queuing (NCQ) is an optional feature, and may be used in both SATA 1.5 Gbit/s and SATA 3.0 Gbit/s devices.
SATA 6.0 Gbit/s
SATA 6.0 is the third generation serial ATA interface. SATA 6.0 increases its data transfer rate to 600 MB/s) This interface is also known as SATA 600, The SATA 600 doubles the maximum throughput of the SATA 300. SATA 600 interface is physically identical to SATA 300 and SATA 150 and like these earlier generations of SATA, it can use existing cables and connectors and some OEMS (Original equipment manufacturer) are expected to upgrade host connectors to attain the higher speed. The new speed may require higher power consumption for supporting chips and the new standard is backward compatible with SATA 3 Gbit/s.
3. External Hard Disk Drives
An External HDD is a portable storage device which is externally connected to a computer using high speed cables. The cables which are used to connect a computer, must be compatible with IDE, SCSI, IEEE 1394 (Firewire), eSATA and USB. The most commonly used cables are USB, eSATA and Firewire. External Hard disks except eSATA drives that use these interfaces consumes the required power from the port through which they are connected. External HDD also supports high-speed data transfer rate.
4. Characteristics of Hard Disk Drive
Before choosing a Hard Disk Drive for your computer, various characteristics such as capacity, interface and RPM of the HDD should be taken into consideration.
The different characteristics of hard disk drives are :
Capacity, Cost – Initially the Hard Disk’s capacity was less and too costly. With the advancement in technology the capacity of the hard disk gradually increased and cost decreased. Now days HDDs are available from 160GB to 4TB.
Interface, Performance – Mainly computer’s use involves loading and saving dala frequently on the hard disk. All these operations require access to the hard disk frequently. The performance of HDD depends on the Hard Drive interface. The hard drive interface is the computer bus that connects the hard disk drive to the processor and memory. Mostly SATA/600 interface is used by desktop hard disk drives.
RPM – Revolutions per Minute refers to how many times the spindle makes a complete 360° turn in one minute. Faster RPM results in quick access time which in turn results in faster read and write access to the drive. IDE HDDs are available in 5400 or 7200 RPM and SATA HDDs are available in 5400, 5900 or 7200 RPM.
All the above mentioned information are written on the label of a hard disk drive and should be provided to the back office when a faulty hard disk is to be replaced. A label on top of the hard disk is shown in the figure 5.7 from where you can derive all these information.
5. Connecting Hard Disk to PC
After going through different types of hard disk drives now we will know how a hard disk drive can be connected to a PC. Follow the below mentioned steps to connect a hard disk drive to PC:
1. Make the jumper settings.
2 Connect the motherboard. interface cable
3. Check from BIOS whether the hard disk drive is detected or not.