The MS-DOS. Managing Disks

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Chapter II

Managing Disks

Managing Disks

* Formatting disks

* System Files

* The root directory

* Removing a disk format

* Creating a System Disk

* Assign or rename a floppy

* Copying a full disk

* Comparison between two disks

* Check the disk status


Disks provide storage long term. The information recorded on the disks remains intact until it is deleted.

The discs store information on magnetic surfaces. In a disk, the magnetic surface is a thin, flexible disk in a protective plastic cover. A hard drive has two or more hard disks stacked one above the other in a sealed box. A hard disk is also called fixed disk Fixed Disk or because it stays in your computer system.

The information on the disks is divided into tracks (tracks), similar to the grooves on a music disc. Each track is a concentric circle that contains a certain amount of information. The more tracks contains a disc can store more information. A hard disk contains much more information than a floppy, because it has more sides and more tracks per side.


Before you can use a diskette, you must first prepare using the FORMAT command. The disk may have been formatted or not before.

When a disk is formatted, the MS-DOS FORMAT SAFE takes a default or secure format. Thanks to insurance formatting, a disk can be restored to its original condition, ie before formatting by UNFORMAT command, provided that no files are stored newly formatted disk.

You can add the / U the FORMAT command to perform an unconditional format. If unconditionally formatting a disk by mistake, there are still chances of regaining the lost information, as long as the program is installed MIRROR before using the FORMAT command.

NOTE: If you use a new hard disk, you must partition (divide the disk into logical parts) before formatearlo.ESTRUCTURA A DISC

Formatting a disk, DOS reserves for its own use the outer race of the face 0.

Then the disk space is separated into two areas:

* The user area: Intended for recording programs or user data

* The System Area: Area reserved for own use DOS

System Area

The System Area occupies about 2% of the total disk space and is further divided into:

* Boot Sector (Boot)

* FAT (File Allocation Table / File Allocation Table)

* The root directory

The boot sector

The boot sector contains a program (BOOT) that starts the computer, turn it on or pressing the keys: CTRL + ALT + DEL.

In turn, the computer performs a series of diagnostic routines to ensure that the hardware is in good condition. If you have a hard disk or floppy disk system, the initialization of the ROM writes the boot record of the disk in the computer’s memory (RAM) and take control over.

The program scans the disk initialization system files:




To verify that the disk is a system disk.

When the system finds the files: IO.SYS and MSDOS.SYS the load on the computer and passes control to the DOS COMMAND.COM. During the process, the files are loaded CONFIG: SYS and AUTOEXEC.BAT, and any such device driver VDISK.SYS.

Once it has finished loading, the DOS prompt appears and the computer is now ready to use it. When the machine can not find the DOS files, send the following error message:

Error in DOS diskette or floppy without

Replace and press any key

And he expected you to search Remove the floppy boot files on the hard drive, or to place a system disk in drive.

System files

* MSDOS.SYS (IBMDOS.COM in IBM version.) – Contains a set of instructions responsible for transferring information to and from the disk drives, thereby enabling the reading and writing of information therein. It maintains the directory. This file has the hidden attribute active.

* IO.SYS (IBMBIOS.COM IBM version.) – Contains programs handlers keyboard, monitor, printer, outputs for communications and other peripherals to be added to the system. They complement the handling capacity of the BIOS (Basic Input and Output System), which is recorded in ROM, adding a set of messages that facilitate the detection of errors in system management. This file has activated its hidden file attribute.

* COMMAND.COM. – Is the shell. It allows the computer to recognize the commands given by the user, executing. Contains also called internal commands.

The File Allocation Table


The File Allocation Table (FAT) is the space below the area of the system and is also generated by the FORMAT command. The FAT is the part of the system that DOS uses to find the tracks of the disk where files are stored. It is so important that the DOS creates two copies of it, if the first breaks were used the second.

The FAT is a table of two columns:


* 1.44 Mb diskettes have 18 sectors per track

* A 512-byte sector comprises

* Most hard drives have 17 sectors per track

* 1.44 Mb disks have one sector per cluster

* Hard drives have 4, 8 or 16 sectors per cluster

The root directory

The root directory contains data files such as name, extension, size, date and time of recording.


When you want to prepare a diskette that is not the system, the FORMAT command has the following parameters:

FORMAT / F: / V: / Q / U

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A: \> FORMAT A: (Default is a secure format)

A: \> FORMAT A: / U (Disables secure format)

A: \> FORMAT A: / F: 720 (Formats to 720 kb)

A: \> FORMAT A: / V: MAC / U (Formatting with plain label and insurance)

A: \> FORMAT A: / Q (quick format)


To recover as much information as possible from a hard disk or floppy disk that has been reformatted, use the UNFORMAT command, as shown in the following example:


Information is retrieved from disk as long as the disc has been subject to a certain format, ie without using / U, or if you installed the program before formatting MIRROR.

You must use the UNFORMAT command immediately after formatting a disk.

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To create a record that can boot your computer system, use the FORMAT or SYS

To create a system disk while performing the same format add the / S the FORMAT command.


A: \> FORMAT A :/ S

Formats a disk in drive A and then transfers the system files to disk

To make a previously formatted disk is a system disk, use the SYS command.


A: \> SYS B:

System discs contain three files of MS-DOS system (IO.SYS, and COMMAND.COM MSDOS.SYS). When you start your computer system, these three files are copied to the RAM of your system. IO.SYS and MSDOS.SYS files are hidden files and were not seen in the directory listing unless you use the / AH accompanying the DIR command. The COMMAND.COM file is in the root directory of the system disk.

IMPORTANT: You can transfer the system files to a single disk using the FORMAT or SYS command. I could not create a system disk by simply copying the files to the Copy command.

Assign or change the name of a floppy

The LABEL command assigns, rename or delete the name of a floppy or hard disk and has 2 parameters:



A: \> LABEL A:


Obtain the name of a diskette

The VOL command gets the name of a hard disk or floppy disk, but does not request a new label as LABEL command does.

The VOL command has one parameter:


A: \> VOL

A: \> VOL C:


DISKCOPY command makes an exact duplicate of any disk, including hidden and system files from a DOS diskette. DISKCOPY command works only with disks that have the same size and also previously formatted destination disk.

DISKCOPY command has 3 parameters:


/ V (Verify): Ensures that the disk is copied correctly performing a copy verification.



A: \> LABEL A: B:

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Comparison between two DISKETTES

Sometimes it is necessary to know if two disks are identical. DISKCOMP compares two disks track by track. DISKCOMP command can be used only with disks of the same size and capacity, can not be used to compare a hard disk with a floppy.

DISKCOMP command has two parameters:



A: \> DISKCOMP A: B: (With two diskette drives)

A: \> DISKCOMP A: A: (With a floppy drive)


The command Check Disk (CHKDSK) verifies that all the files have been recorded correctly. CHKDSK analyzes the directory by comparing their elements with the locations and the lengths of the files and reports the errors it finds.

The CHKDSK command has four parameters:


: Is the name of the file whose storage you want the check MS-DOS.

/ V: Displays the name of the files and directories on the disk

/ F: Indicates the DOS to correct any errors found in the directory if so specify when you find the error.




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Miguel A. Candela Chavez