progress bar code in vb.net Figure 5-4 Close-up of a hard drive, showing platters and read-write head armature in Software

Generator Code 3/9 in Software Figure 5-4 Close-up of a hard drive, showing platters and read-write head armature

Figure 5-4 Close-up of a hard drive, showing platters and read-write head armature
Decode Code-39 In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Printing Code 39 In None
Using Barcode generator for Software Control to generate, create USS Code 39 image in Software applications.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website.
Decoding Code-39 In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Creating Code 39 Full ASCII In Visual C#.NET
Using Barcode printer for .NET Control to generate, create Code 3 of 9 image in VS .NET applications.
Premises Technologies
Code39 Generation In .NET
Using Barcode creation for ASP.NET Control to generate, create Code39 image in ASP.NET applications.
Drawing Code 3 Of 9 In VS .NET
Using Barcode generation for .NET framework Control to generate, create Code 39 Full ASCII image in .NET applications.
Premises Technologies
Code 39 Extended Creator In VB.NET
Using Barcode printer for .NET framework Control to generate, create USS Code 39 image in VS .NET applications.
GTIN - 12 Generator In None
Using Barcode creator for Software Control to generate, create UPC Code image in Software applications.
Figure 5-5 Schematic diagram of a hard drive As the platters spin, the read-write heads access the magnetized surfaces of each platter, writing information to and reading information from them.
EAN 13 Generator In None
Using Barcode maker for Software Control to generate, create EAN-13 Supplement 5 image in Software applications.
Code 3/9 Maker In None
Using Barcode maker for Software Control to generate, create Code 39 Extended image in Software applications.
When the operating system formats a disk, it logically divides the disk into what are called cylinders, tracks, and sectors, as shown in Figure 5-6. It then uses those delimiters as a way to store and recall files on a drive, using three dimensions. When the operating system (OS) writes the file to the disk surface, there is every possibility (in fact it is likely) that the file will not be written to the surface in a contiguous stream of bits. Instead, the file may be broken into pieces, each of which may be written on a different part of the disk array. The pieces are linked together by the operating system using a series of pointers, which tell the OS where to go to get the next piece of the file when the time comes to retrieve it. The pointer, of course, is a cylinder:track:sector indication.
Printing DataMatrix In None
Using Barcode maker for Software Control to generate, create ECC200 image in Software applications.
Generating GS1 128 In None
Using Barcode generation for Software Control to generate, create EAN 128 image in Software applications.
Figure 5-6 Cylinders, tracks, and sectors on a typical disk
USD-3 Generator In None
Using Barcode printer for Software Control to generate, create Code 93 Full ASCII image in Software applications.
Paint EAN 128 In Visual Basic .NET
Using Barcode encoder for .NET framework Control to generate, create EAN / UCC - 14 image in Visual Studio .NET applications.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website.
EAN128 Generation In C#.NET
Using Barcode creator for VS .NET Control to generate, create EAN / UCC - 14 image in VS .NET applications.
Recognizing Bar Code In Visual Studio .NET
Using Barcode scanner for .NET Control to read, scan read, scan image in .NET applications.
Premises Technologies
Barcode Maker In Visual Studio .NET
Using Barcode generator for ASP.NET Control to generate, create bar code image in ASP.NET applications.
Data Matrix ECC200 Decoder In Visual Basic .NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in VS .NET applications.
5
Bar Code Generator In None
Using Barcode creator for Font Control to generate, create bar code image in Font applications.
Print Barcode In Java
Using Barcode generator for BIRT reports Control to generate, create bar code image in Eclipse BIRT applications.
Cylinders, tracks, and sectors are relatively easy to understand. A track is a single writeable path on one platter of the disk array. A cylinder is a stack of tracks on multiple platters. And a sector is a pie slice of the disk array. With a little imagination it is easy to see how a file can be stored or located on a disk by tracking those three indicators. It should also be easy to see now how some of those wonderful applications like Norton Utilities work. When you direct your computer to erase a file, it doesn t really erase it; it just removes the pointers so that it is no longer a registered file and can no longer be found on the hard drive. What file restore utilities do is remember where the pointers were when you told the computer to erase the file. That way, when you beg the computer to find the file after you ve done something stupid (this is always the trick of killing the chicken and lighting candles), the utility has a trivial task: Simply restore the pointers. As long as there hasn t been too much disk activity since the deletion and the file hasn t been overwritten, it can be recovered. Another useful tool is the disk optimization utility. It keeps track of the files and applications that you, the user, accesses most often while at the same time keeping track of the degree of fragmentation that the files stored on the disk are experiencing. Think about it: When disks start to get full, there is less of a chance that the OS will find a single contiguous piece of writeable disk space and will therefore have to fragment the file before writing it to the disk. Disk optimization utilities perform two tasks. First, they rearrange files on the disk surface so that those accessed most frequently are written to new locations close to the spindle, which spins faster than the outer edge of the disk and, therefore, is accessible more quickly. Second, they rearrange the file segments and attempt to reassemble files or at least move them closer to each other so that they can be more efficiently managed. OK, enough about hard drive anatomy. Other forms of secondary memory include those mentioned earlier writeable CDs, DVDs, zip disks, floppies, and nonvolatile memory arrays. As I mentioned, this has become a big business because these products make it relatively easy for users to back up files and keep their systems running efficiently.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website.
Copyright © OnBarcode.com . All rights reserved.