Question

What are the different types of hard drives used in personal computers. [20 marks]

Answer 1

In General, we can classify types of Hard Drives into four Categories:

- PATA (Parallel Advanced Technology Attachment)

- SATA (Serial Advanced Technology Attachment)

- SCSI (Small Computer System Interface)

- SSD (Solid State Drives)

Let us go through them one by one.

Parallel Advanced Technology Attachment

PATA were the first types of hard drives and it used the Parallel ATA (Advandced Technology Attachment) interface standard to connect to computers. These drives are also referred to as Integrated Drive Electronics (IDE) and Enhanced Integrated Drive Electronics (EIDE) drives. They provided a common drive interface technology for connecting hard drives and other devices to computers.

- PATA Drives have usually 40 pins.
- Data transfer rate can go up to 133MB/s
- Maximum 2 devices can be connected to a drive channel.
- It sends 8 bit data at a time.

Serial Advanced Technology Attachment

SATA hard drives have replaced the PATA drives in desktop and laptop computers. The main physical difference between the two is the interface, although their method of connecting to a computer is the same.
- They can transfer data faster than PATA types by using serial signaling technology.
- It sends data bit by bit.
- They offer generally 300MB/sec transfer rate.
- They have usually 7 pins, 4 pins in pair of two for sending and receiving data and rest 3 pins are grounded.
- They consume less power. They only require 250 mV as opposed to 5V for PATA.

Small Computer System Interface

SCSI drives are quite similar to IDE hard drives but they make use of the Small Computer System Interface to connect to the computer. SCSI drives can be connected internally or externally. Devices that are connected in a SCSI have to be terminated at the end. Here are some of their advantages.
- They have usually 50 to 68 pins.
- They offer generally 640MB/sec transfer rate.
- Maximum of 16 drives can be connected in a single scsi cable. Each hdd have a 8 bytes hexadecimal code known as WWN (worldwide name) for its identification in the cable.
- Good for storing and moving large amounts of data.

Solid State Drives

SSD are the latest in drive technology. They are totally different from the other drives in that they do not consist of moving parts. They use the Flash memory Technology and do not store data using magnetism. They use integrated circuits or semiconductor devices to store data.
- They offer instant-load performance, meaning faster boot times, faster application loading times, and better system responsiveness.
- They're more durable.
- They're have longer battery life.
- They weigh less than convention HDD, thus they are easier to carry.