Presented by: Tristan Marcellana

What is A ?

What is a Hard Drive ? 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 .

Used for storing and retrieving digital information using rapidly rotating disks (platters) coated with magnetic material.

Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just

a few megabytes.

They were originally called "fixed disks" or "Winchesters"

(a code name used for a popular IBM product).

They later became known as "hard disks" to distinguish them from

"floppy disks."

A Hard disk is really a set of stacked "disks," each of which, like phonograph records, has data recorded electromagnetically in concentric circles or "tracks" on the disk. A "head" (something like a phonograph arm but in a relatively fixed position) records (writes) or reads the information on the tracks. Two heads, one on each side of a disk, read or write the data as the disk spins. Each read or write operation requires that data be located, which is an operation called a "seek."

A hard disk/drive unit comes with a set rotation speed varying from 4500 to 7200 rpm. Disk access time is measured in milliseconds.

The physical location can be identified with cylinder, track, and sector locations, these are actually mapped to a logical block address (LBA).

There are two ways to measure the performance of a hard disk:

1.) Data rate

- The data rate is the number of bytes per second that the drive can deliver to the CPU. Rates between 5 and 40 megabytes per second are common.

2.) Seek time

- The seek time is the amount of time between when the CPU requests a file and when the first byte of the file is sent to the CPU. Times between 10 and 20 milliseconds are common.

Data is stored on the surface of a platter in

sectors and tracks. Tracks are concentric

circles, and sectors are pie-shaped wedges on a

track, like this:A Typical track is shown

in yellow; a Typical sector is shown in blue. A sector contains a fixed

number of bytes -- for example, 256 or 512.

Either at the drive or the operating system level,

sectors are often grouped together into

clusters.

AT Attachment (ATA)AT Attachment (ATA), was by far the

most common hard disk interface used in PCs from the early 1990s through 2003. ATA is sometimes called Parallel ATA or PATA, to differentiate it from the newer Serial ATA (SATA) interface. ATA is still used in new systems, although it is being superseded by SATA. ATA is also often called IDE (Integrated Drive Electronics).

Serial ATA (SATA)Serial ATA (SATA) is a newer technology

that is replacing ATA. SATA has several advantages over ATA, including smaller cables and connectors, higher bandwidth, and greater reliability.

SATA is generally compatible with ATA at the software level, which means that the operating system ATA drivers work with either SATA or ATA interfaces and hard drives.

Small Computer System Interface (SCSI)

SCSI is used in servers and high-end workstations, where it provides two advantages: Improved performance relative to ATA and SATA in multitasking, multiuser environments, and the ability to daisy-chain many drives on one interface. High performance desktop systems.

Short Quiz :1.) Original term for Hard Disk Drive.

2.) The Hard Drive was First Introduced on _____ .

Nos. (3-4) Two ways to Measure the Performance of a Hard Disk .

5.) Standard Term for [SCSI]

6.) Platters is Coated with __________ which is used to Store and Retrieve Digital Information.

7.) A Hard Drive Disk Unit has a Rotation Speed Varying from ________ RPM.

8.) Standard Term for [LBA].9.) The Number of Bytes per Second

that the Drive can Deliver to the CPU.10.) Amount of Time Between when the

CPU Requests a File.

Answers:1.) Fixed Disks or Winchesters.2.) September 13, 1956.Nos. (3-4) *Data Rate *Seek Time5.) Small Computer System InterFace6.) Magnetic Material7.) 4500-7200 RPM8.) Logical Block Adress9.) Data Rate10.) Seek Time