Function To Change the Parameters of DBR

/* Function To Change the Parameters of DBR */

Recover_with_values()
{
int val =0;

/* Jump Code of 3 Bytes For Floppy */
b.code[0] = 0xEB;
b.code[1]= 0x3E;
b.code[2]= 0x90 ;

/* System Id of 8 Bytes */
strcpy(b.system_id, "+05PSIHC");

/* Bytes Per Sector = 512 */
b.bytes_per_sec = 512;

/* Sector per Cluster for 1.44M 3.5" Floppy = 1 */
b.sec_per_clus = 1;

/* Number of Reserved Sectors = 1 */
b.res_sec =1;

/* Number of FAT Copies = 2 */
b.fat_copies =2;
/* Number of Root Directory Entry = 224 */
b.root_dir_entry =224;

/* Number of Sectors on Disk = 2880 */
b.no_sects =2880;

/* Media Descriptor Byte For Floppy = F0 (H) */
b.format_id =0xF0;

/* Sectors Per FAT = 9 */
b.sec_per_fat =9;

/* Sectors Per Track = 18 */
b.sec_per_trk =18;

/* Number of Sides = 2 */
b.no_sides =2;

/* Number of Special Reserved Sectors (or Hidden
Sectors) = 0 */
b.no_sp_res_sect =0;

/* Use For Floppy Disk*/
val = abswrite ( 0, 1, 0, &b ) ;

if ( val == -1 )
{
printf ( "\n Disk Write Error...bad sector\n" ) ;
printf ( " Disk was not Recovered." ) ;
exit ( 1 ) ;
}

return 0;
}

display_info()
{
printf ( "\n Jump Code (Hex) = %X%X%X (H)\n",
b.code[0],b.code[1],b.code[2]);
printf ( " System ID = %s\n", b.system_id ) ;
printf ( " Bytes per sector = %d\n", b.bytes_per_sec ) ;

printf ( " Sectors per cluster = %d\n", b.sec_per_clus ) ;

printf ( " Reserved sectors = %d\n", b.res_sec ) ;

printf ( " FAT copies = %d\n", b.fat_copies ) ;

printf ( " Root directory entries = %d\n", b.root_dir_entry ) ;

printf ( " No. of sectors on disk = %u\n", b.no_sects ) ;

printf ( " Media Descriptor Byte = %X\n", b.format_id ) ;

printf ( " Sectors per FAT = %d\n", b.sec_per_fat ) ;

printf ( " Sectors per track = %d\n", b.sec_per_trk ) ;

printf ( " No. of sides = %d\n", b.no_sides ) ;

printf ( " No. of reserved sectors = %d\n", b.no_sp_res_sect ) ;
return 0;
}

Comments on coding:

The structure boot is used to access the DBR, to read-write the parameters of the disk. The function display_info(), displays the various parameters of the disk, reading from the DBR. The function Recover_with_values() is used to modify and recover the parameters of DBR of Floppy.

The values used by the function Recover_with_values(), are for parameters of 1.44MB, 3 ½ inch floppy disk’s DBR. The description of these values has been given in the table given next:

Sample Chapters from book DATA RECOVERY WITH AND WITHOUT PROGRAMMING by Author Tarun Tyagi

Publishers of the Book Number of Pages ISBN Price of the Book BPB Publications, New Delhi, India 540 81-7656-922-4 $69.00 (Including Shipping Charges, Cost of Book and Other expenses, Free Source Code CD included with the Book)

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