The document provides information about hard disk drives, including: - Hard disk drives store digitally encoded data on rapidly rotating platters with magnetic surfaces. Data is stored as binary 0s and 1s. - Disk structures include tracks, sectors, cylinders, and clusters. Tracks are circular areas on disks, sectors are the smallest storage units, cylinders group same tracks, and clusters are groups of sectors. - Performance is measured by latency, data rate, and seek time. Latency depends on rotation speed, data rate is bytes/second, and seek time is retrieving requested data. - Common interfaces are IDE, SATA, and SCSI, which have different connectors and data transfer speeds.

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3. Introduction
TITLE: HARD DISK DRIVE
CLASS: MASTER COMPUTER SCIENCE (MCS)
SUBJECT: OPERATING SYSTEM
PRESENT BY ZUBAIR FAROOQ
DATE 20 AUGUST, 2015

4. Hard Disk
 A hard disk drive is a non-
volatile storage device that
stores digitally encoded data
on rapidly rotating platters with
magnetic surface.
 Its stored in 0 (or) 1.
 The hard disk drive was
originally invented by an IBM
team led by Rey Johnson in
1956.

5. Hard Disk Internal Structure

6. Disk structures
 Tracks-
 circular areas of the disk
 Data first written to outer most track
 Over 1000 on a hard disk
 Sectors-
 Divides tracks sections
 Sectors are the smallest physical storage units on a disk-
 Each sector stores 512 bytes of data
 Cylinders-
 Logical groupings of the same track on each disk surface in a disk
unit
 Track create cylinder inside the hard disk.
 Clusters (Blocks) -
 Groups of sectors used by operating system
 64 sectors in one cluster

7. Disk / Platter
 Each platter has 2 surfaces
 Platter is made from aluminum, ceramic, or class,
coated with a magnetic materials such as iron oxide.
 Platter spin between 4,800 to 15,000 round per
minute(RPM)
 Platter contain number of tracks and sectors.

8. Performance characteristics
 There are three ways to measure the
performance of a hard disk:
 Latency
Latency is the delay for the rotation of the
disk to bring the require disk sector under the
read-write mechanism.
It depends on rotational speed of a disk,
measured in revolutions per minute (rpm).

9. Performance characteristics
 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.
 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

10. Hard Drive Interfaces Overview
 IDE (integrated drive electronics)
 SATA (Serial Advanced Technology Attachment)
 SCSI (small computer system interface)

11. IDE (Integrated Device Electronics)
 1. It has a 40 pin connector.
 2. Data transfer rate is 133MB/s.
 3 .When installed this type of hard drives ensure that the jumpers are
correctly configured.
 Also known ATA (Advance Technology Attachment)

12. SATA (Serial Advanced Technology
Attachment)
 It has a 7 pin connector.
 It is the latest high-speed type of hard drive connectors.
 Data transfer rate is 300Mb/s.

13. SCSI (Small Computer System Interface)
1. It has a 50 or 68 pin connector.
2. The data transfer rate is 600Mb/s .

14. List of Hard Drive Manufacturers

15. Questions
Feel Free to ask any Questions.