Copyright © 2007 Heathkit Company, Inc. All Rights Reserved PC Fundamentals Presentation 15 – The Hard Drive

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

3 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 Drive

5 Start with a non-magnetic platter. Floppy Disk - Mylar Hard Disk - Metal, Ceramic, or Glass

6 Coat with a thin layer of magnetic material.

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

8 Track 0 Track 1 Track 79

9 Side 1, Track 0 Side 1, Track 0 Side 2, Track 0 Side 2, Track 0

10 Most Hard Drives Have Multiple Platters. Platter1, Track1 Platter2, Track1 Platter3, Track1 Platter4, Track1

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

12 Read\Write Head Read\Write Head Platter

13 Read\Write Head Read\Write Head Disk Read/Write Head Read/Write Head

14

15

16 One Sector = 512 Bytes

18 1:3 Interleave

:1 Interleave

20 Cluster

21 Cluster 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.

22 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.

23 Formatting Low Level Formatting - Performed by the Disk Drive Manufacturer. High Level Formatting - Performed by the PC User via the FORMAT Command.

24 Blank Disk Sectors and tracks defined Sectors and tracks defined Low-Level Formatting

25 Low 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.

26 High Level Formatting Originally performed by the vendor of the computer. Creates Boot Record, FAT, and the Root Directory. Performed with the FORMAT Command.

27 Partitioning 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.

28 The Hard Drive Case Should Not be opened.

29 Typical Hard Drive Connectors 40-pin IDE Cable Connector 8-pin Jumper Connector 4-pin Power Connector

Copyright © 2007 Heathkit Company, Inc. All Rights Reserved PC Fundamentals End