Copyright © 2007 Heathkit Company, Inc. All Rights Reserved

PC Fundamentals

Presentation 15 Presentation 15 –– The Hard Drive The Hard Drive

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ObjectivesObjectives

At the end of this presentation, you will be able to:

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Explain the construction and operation of a basic hard disk drive.

Identify the major components inside the hard drive case.

Define track, cylinder, sector, cluster, FAT, format, and partition.

Explain the difference between low-level and high-level formatting.

Explain the purpose of FDISK and DISKPART.

Identify the connectors on a typical hard drive.

Hard Drive vs. Floppy DriveHard Drive vs. Floppy Drive

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Start with a non-magnetic platter.Start with a non-magnetic platter.Floppy Disk - MylarFloppy Disk - MylarHard Disk - Metal, Ceramic, or GlassHard Disk - Metal, Ceramic, or Glass

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Coat with a thin layer of Coat with a thin layer of magnetic material.magnetic material.

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The disk surface is dividedThe disk surface is divided into into tracks.tracks.

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Track 0Track 0

Track 1Track 1

Track 79Track 79

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Side 1,Track 0Side 1,Track 0

Side 2,Track 0Side 2,Track 0

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Most Hard Drives Have Multiple Platters.Most Hard Drives Have Multiple Platters.

Platter1, Track1Platter1, Track1

Platter2, Track1Platter2, Track1

Platter3, Track1Platter3, Track1

Platter4, Track1Platter4, Track1

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The eight track 1’s are referred to The eight track 1’s are referred to collectively as “Cylinder 1.”collectively as “Cylinder 1.”

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Read\WriteHead

Read\WriteHead PlatterPlatter

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Read\WriteHead

Read\WriteHead

DiskDisk

Read/WriteHead

Read/WriteHead

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15

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One Sector =512 Bytes

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551313

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44

2233

77

66

889910101111

1212

1414

15151616 1717

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1:3 Interleave

88

771313

1414

9915151010

1616

1111

1717

1212

55

11

22

3344

66

19

11

44

2233

77

66

1:1 Interleave

551313

889910101111

1212

1414

15151616 1717

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ClusterCluster

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ClusterCluster

The smallest unit of disk space that MS-DOS could allocate to a file.

It consists of one or more sectors.Cluster size is determined by the OS when

the disk is formatted.Generally, the larger the disk drive; the

more sectors per cluster.

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File Allocation Table (FAT)File Allocation Table (FAT)

The OS’s road map to the disk drive. How DOS (and early versions of Windows) kept

track of which clusters belonged to which files. How DOS kept track of bad sectors. Two copies maintained and kept up to date by

DOS. Still accessible by most operating systems today,

although the more capable NTSC (Windows NT file system) is preferred by Windows NT/2000/XP.

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FormattingFormatting

Low Level Formatting - Performed by the Disk Drive Manufacturer.

High Level Formatting - Performed by the PC User via the FORMAT Command.

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Blank DiskBlank Disk Sectors and tracks definedSectors and

tracks defined

Low-Level Formatting

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Low Level FormattingLow Level Formatting

Performed at the factory.Converts the single blank surface into

tracks and sectors.Finds and remaps bad spots on the disk so

that the operating system can avoid them.

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High Level FormattingHigh Level Formatting

Originally performed by the vendor of the computer.

Creates Boot Record, FAT, and the Root Directory.

Performed with the FORMAT Command.

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PartitioningPartitioning

Makes the hard disk compatible with the operating system.

Prepares the hard disk for high-level format.Divides the hard disk into two or more

partitions or makes it all one large partition.Performed with the FDISK or DISKPART

command.

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The Hard Drive Case Should Not be The Hard Drive Case Should Not be opened. opened.

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Typical Hard Drive ConnectorsTypical Hard Drive Connectors

40-pin IDE CableConnector

8-pin Jumper

Connector

4-pin Power

Connector

Copyright © 2007 Heathkit Company, Inc. All Rights Reserved

PC Fundamentals

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