Inferno #07
31 мая 2005 |
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Likbez - The location of partitions on your hard drive.
Location of sections hard drive ZET-9 12.03.2005 Last edit 22.05.2005 Information obtained by experiment and cha partially from the books on MS-DOS. As for the standard PC-screws t.e.vin Comrade, sections of which were created on the PC with using the program fdisk, Partition magic and similar to them. Digression Standard partitioning mi in fdisk. fdisk.exe - a standard program It is also on a boot diskette MS-DOS. After the program's operation on the screw ALL INFORMATION WILL BE LOST! 1) Create a primary partition (he calls Xia "first"). If he is the only it removes the entire screw. If you need more sections, then it removes the part of the screw - For example, 20%. In the fdisk can only create one primary partition. Therefore, if needed More sections, we turn to the creation of additional positive. 2) Create an additional section - a It is usually allocated by the remaining part screw. Now begin to create more sections - they will be created as a supplement to internally lnogo section. In the fdisk they are called logical drives. 3) Create the logical drives in any finite lichestve (one) thing to them about total volume did not exceed the amount of additional the second partition (the program still is not on zvolit do). As a result, we get to screw one major section and some additional separation fishing. With the help of Partition Magic can zhno do a lot of things, while in some In some cases infa on the screw remains - it the main difference between it and fdisk. And one more thing difference: you can create a few basic sections - a maximum of 4 (if not to create additional information), or on already existing tvuyuschem screw (which is a major section and a few more) to create 2 more major sections (eg, by reduce the length of the first major separation la) - then the screw will be 3 main and several additional sections. Main Sections The very first sector on the screw - it's MBR (Master boot record - Master Boot Record). At the beginning of a sector may be ka Coyte PC-shny boot length # 01BE bytes. # 01BE at offset from the beginning of this (the first Vågå) sector is a table separated crystals of length 64 bytes. Last 2 bytes in Gaza - # 55, # AA. If they are not, then this screw "nonstandard" (for PCs), and define Tb, which have sections on the screw, but rather all second, it does not, but you can try. Partition table Its length is 64 bayta.Vsego it discharged records for four razdelov.Na every time Affairs - 16 bytes. The record contains a several fields with the data. Offset Length Field Name from the beginning of the field, Table B 0 1 signs of activity section - the flag. ; Accepts values 0 (inactive) or # 80 (Active). The active can be only one of the sections. BIOS on the PC will produce download code from this section. March 1 beginning of the section in format CHS. ; These 3 bytes contain the values for registration ditch the cylinder heads and sectors (Cyl, Head, Sec - abbreviated CHS), which should send the screw to read the first sector of the Forum: - 1-byte - is the number of heads (used is four least significant bits); - 2-byte: lower 6 bits - the number of sectors; Bits 6, 7 - are bits 8, 9 cylinder number Register for a cylinder (they correspond bits 0 and 1 in the register Cylinder Hi); - 3rd byte - are bits 0 .. 7 rooms cylinder pa for the registers of the cylinder (the byte is shown pertains to the register Cylinder Low). Offset Length Field Name from the beginning of the field, Table B April 1 byte System. ; Byte indicates the type of partition. Values: 0 - unusual section; 1 - primary partition DOS (FAT12) (main) size 0 .. 15 MB; 4 - primary partition DOS (FAT16) (main) size 16 .. 32 MB; 5 - Advanced razd.DOS (optional) size 0 .. 2 GB; 6 - "huge" razd.DOS (> 32Mb) (main) size 32 MB .. 2 GB (FAT16); # 0B - major (FAT32), Size 512 MB .. 2 terabytes (Value used in OS / 2); # 0C - basic (FAT32), Size 512 MB .. 2 terabytes (This value is now used in all Windows for large screws); # 0E - basic (FAT16), size 32 MB .. 2T; # 0F - Extended (optional) 0 .. 2T; # 83 - denoted as the main section with broken rotor system Linux; # 85 - so designated partition for swap with broken screws on Linux. Offset Length Field Name from the beginning of the field, Table B May 3 End section in the format of CHS. ; These 3-byte values for the registers Goals ki, sectors and cylinders indicate the end Forum: - 1-byte - is the number of heads (used is four least significant bits); - 2-byte: lower 6 bits - the number of sectors; Bits 6, 7 - are bits 8, 9 cylinder number Register for a cylinder (they correspond bits 0 and 1 in the register Cylinder Hi); - 3rd byte - are bits 0 .. 7 rooms cylinder pa for the registers of the cylinder (the byte is shown pertains to the register Cilinder Low). Offset Length Field Name from the beginning of the field, Table B August 4 Number of sectors to beginning of the section. ; Number of sectors of 512 bytes, which must be skip to the beginning of this razdela.Eto on les used in LBA mode instead valued th from the 'beginning of partition in the format of CHS ". In fact, this block number in the mode LBAadresatsii (blocks are numbered from zero). April 12 Number of sectors in this section. The length of the section in the sectors of 512 bytes. Here are 16 bytes in each entry for each of the existing partitions. Sections can be determined by the system byte: if it is 0 - hence, the section No, if it is 5 - so this additional section are positive, another value - the main section. The coordinates beginning section (CHS or LBA) to load the sector - this is the first sector of the partition, it's called Boot Record (MBR) or Boot Sector (zag ruzochny sector). Format Boot-sector distribution see at the end of the article. Additional sections To work with additional sections should: 1) In the MBR, partition table to find the section with the value system byte to 5 (Or # 0C, or # 0F) - a byte at offset 4 from the recording of this section; 2) Get information about this topic from field "the beginning of the section (in the format of CHS or LBA). This information is for additional section does not point to the beginning of supplement lnogo section, and the sector, which contains contains SBR (Secondary Boot Record). When operating in LBA mode to remember this value, you'll need it later. We call it ADRES_LBA; 3) Download sector SBR.Etot sector has em structure is almost the same as the MBR, but not contains a boot loader and partition table (Located at offset # 01BE from the beginning this sector), only the first two records (in contrast to the MBR, where the use form a 4 records) of 16 bytes each. The last 2 bytes of the sector are SBR # 55, # AA. Records contain fields similar to those fields in the MBR. In this case, the first record containing contains information about the additional time Indeed, while the second entry points to the following schuyu SBR (if you have multiple supplement lnyh sections). The SBR for the latest dopo lnitelnogo section is used only first record; 4) If this is an additional section, that we need, go to step 5. Otherwise: looking for the following additional section; taken from the 2 nd table entries value of "top section of the corresponding schego field, and if the mode of CHS, then immediately upload the following SBR. In LBA mode must add this value to the ADRES_LBA and assign the result variable ADRES_LBA - and only after this th download SBR. Next, go to nachalo this paragraph; 5) Take out a second record in the table separated fishing beginning of this section of the corresponding ing fields and load the Boot-sector of the section. Attention! Box top section of the form mate CHS "(at offset 1 from the beginning of recording) indicates the first sector of the additional Indeed razdela.Prosto use it to Download Boot-sector. Box top section in a format LBA "(for offset 8 from the beginning of record) contains a number of Lo sectors prior to the additional time case, but not from the beginning of the hard drive (!), and from values ADRES_LBA. Therefore, to obtain the actual number of sectors to start to Executive section, we add these two value and then load the Boot-sector. Now, when loaded with Boot-sector nuzh Nogo us section, we take from it all information tion on the FAT file system on this time case. The structure of this section. - 1 st sector of the partition - this is Boot-sector; - A few unused sectors (which may be missing - they count learn from two bytes at offset 14 from the start of the Boot Sector); - 1-th copy of FAT; - 2-th copy of the FAT; - The root directory; - Data. Note: When using the hard drive on the other file system (not FAT) is necessary in driver, the hard drive to store the value lichestva sectors before partition (if format is used CHS, it must be recalculated a thief in the top section of the CHS format LBA), and when referring to the section the driver will be at ppend this value to the number of sectors to tory to download / burn. Exactly just do it at work with an additional lnymi partitions FAT (sm.primechanie to displacements scheniyu # 1C in the Boot-sector). Format Boot-sector Attention! The format of this sector is valid Liv file systems FAT12 and FAT16. Here, the length of the sector - 512 bytes. Boot-sector - is the first sector on the dis Kothe file system FAT12 (floppy MS-DOS). On the disk with the file system FAT12 or FAT16 is the first sector of the partition (Not to be confused with the first sector of your hard drive, in which is located MBR). Contains the following data: Offset Length Purpose 0 3 transition team at the code loader. August 3 system identifier (a name program - the formatter). ; Usually "MSWIN4.1". # 0B 2 Length in bytes of the sector. ; Usually 512. # 0D 1 Number of sectors cluster. ; Floppy = 1; ; For HDD (FAT12) = 8; ; For HDD (FAT16) can 4,8,16,32,64. # 0E 2 Number reserved different sectors. ; This is the number of sectors to 1 second copy of FAT (on floppy disk is actually a number of sectors where FAT; hard drive - the number of sectors from the beginning of this section). It can not be 0. # 10 1 Number of FAT. , Usually 2. # 11 2 Maximum effort number of files in root directory. ; Floppy usually 56; ; For the HDD is usually 512. # 13 2 Total number of sectors on the disk. ; To a floppy disk and hard drive for up to 32 MB RAM, and if> 32 MB, then this field soda rzhit 0, 0). # 15 1 Code format (Byte descriptor type of disc) The value of this byte is: # F0 - floppy disks, 2 sides, 18 sectors on track; # F8 - Hard drive; # F9 - floppy disks, 2 sides, 15 sectors on track; # FC - A floppy disk, 1-sided, 9 sectors on track; # FD - A floppy disk, 2-sided, 9 sectors on track; # FE - A floppy disk, 1-sided, 8 sectors on track; # FF - A floppy disk, 2-sided, 8 sectors on track. # 16 2 Number of sectors one FAT. # 18 2 Number of sectors one track. ; Floppy = 9; ; For the HDD - this parameter Sec. # 1A 2 Number of heads on disk. ; For the HDD - this option Head. # 1C 4 Number of special (Hidden) sectors. ; Very important parameter for the hard drive - a number of sectors before partition. Attention! For the main sections of this real finite number of sectors from the beginning of the hard drive before this section. For additional sections This number coincides with the value of the field Co. lichestvo sectors prior to the section, taken Tym from the partition table in the SBR. # 20 4 Number of sectors on the disk. ; Used if the size of the hard drive> 32M. 1 ID # 24 drive (drive number to the hard drive in the BIOS). ; First = # 80. # 25 1 reserve. # January 26 Signature Extended sector, ie only that wrote that DOS 4.0 and above, includes here # 29. # April 27 Serial number of the volume. ; Serial number - written by formatirova SRI disc contains a unique number and date. # 26 11 The name of the disk. # 36 8 Contains "FAT12" or "FAT16". Supplement: It was noted that hard drives supported equation describing mode LBA, when you create them again Delov get the next option. Beginning of the first primary partition is always is set to # 3F (in the "number of cross Ktorov before partition) and cylinder 0, head 1, sector 1 (in the "beginning of the partition format CHS "). This was observed in the following screws: DHAA-2270 (258 Mb); IBM-DB0A-2540 (541 Mb); IBM-20 (20 Gb); Maxtor (40 Gb); Western Digital (160 Gb). As a result - some of the screws (Small - 200-500 meters), not as a result regime CHS use the Start section format CHS ", as in fact to chalo section is not there, but you can use the "number of sectors before the separation la, "but only if the screw under the supported the regime of LBA (ie working with him mode LBA). More about Boot-sector Under the Boot-sector will understand all the cross Ktorov before the first primary partition. On the screws with FAT16 is used only is the first sector, the rest of the sector to beginning of the section are free. On the screws with FAT32, but the very first sector, the sector is still in use 6 - there holds a copy of the first sector (to entropy of the partition table), and in sector 2 contains contained additional information on the number space of free disk space on the first free cluster on the disk. The contents of the 2 nd sector (assuming that the sector with the first): Offset Length Value 0 4 # 41, # 61, # 52, # 52 ; Dop.sektora Id. 4 480 ; Field is reserved (zero). # 01E4 4 # 61, # 41, # 72, # 72 ; Dop.sektora Id. # 01E8 4 ; Free clusters on diske.Esli this field has a value of # FFFFFFFF - need to calculate. # 01EC 4 ; Number of cluster on the disk from which the starting nat find a free cluster. If this field has a value of # FFFFFFFF - hence should compute. 12 # 01F0 ; Field is reserved (zero). # 01FC 4 # 00, # 00, # 55, # AA ; Dop.sektora Id.
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