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Particijske tablice i njeni dijelovi
sljedeći tekst našao sam na jednoj web stranici, stavit cu i link, podebljani dio me zanima dal mi moze netko objasnit sta znaci, nisam expert u engleskom pa me taj dio muci, ostatak sam skuzio :) treba mi za maturalni, hvala
A partition descriptor is a 16-byte structure with the following fields: 0 Boot Indicator [This byte is used by some boot loaders to indicate which of the primary partitions should be booted.] 1-3 Begin CHS [Cylinder/Head/Sector address of the partition start. For the format, see below.] 4 Partition Type [This type generally indicates what operating system or file system can be found on the partition, or what the partition is used for. For a list, see the list of known partition types.] Here we shall always give types in two hexadecimal digits. Types 05, 0F and 85 (hex) indicate an extended partition. [DOS only knows about 05, Windows 95 introduced 0F, Linux introduced 85.] 5-7 End CHS [Cylinder/Head/Sector address of the partition end.] 8-11 Partition Start The 4-byte little-endian value of the starting sector number (counting from 0) of the partition. 12-15 Partition Size The 4-byte little-endian value of the size in sectors of the partition. If this value is zero, the partition descriptor should be ignored [and all other values in the descriptor should be zero as well]; in this case the partition descriptor is called unused. http://www.win.tue.nl/~aeb/partition..._tables-2.html |
The 3-byte CHS adresses are encoded as follows: The first byte contains h, the head number, a value in the range 0-255. The second byte contains in its last six bits s, the sector number, a value in the range 1-63. The high order two bits of the second byte, followed by the eight bits of the third byte form c, the cylinder number, a value in the range 0-1023. In C-like code:
h = byte1; s = byte2 & 0x3f; c = ((byte2 & 0xc0) << 2) + byte3; For a disk with C cylinders, H heads, and S sectors per track, the linear address corresponding to a CHS address (c,h,s) is found as c*H*S + h*S + s - 1. [Since CHS addresses have 24 bits only, they cannot address more than 2^24 sectors, which is insufficient for modern disks. Moreover, it is often unclear what values should be used for C, H, S. Thus, these CHS addresses should be ignored.] i taj me dio zanima ali samo ovaj treci dio za cilindre ne kuzim kak se racuna... |
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source: wiki |
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tnx... jel mi mos jos samo onaj dio o racunanju cilindara, kak se racuna, skuzio sam za s i h al me c muči :/ a :google: mi nije pomogo... |
Evo nacrtao sam na papiru i napisao objasnjenje. Ono sto sam zaboravio napisati na papiru je to da je maska koja se dobija sa c0 11000000. Kada byte2 pomnozis tom maskom ostanu ti samo najviša 2 bita drugog bajta setovana a svi ostali bitovi se resetuju. Dalje sam napisao sta se desava i kako.
http://www.dodaj.rs/t/2O/14/3pVZCPVv/aaa-001.jpg EDIT: Krajnji raspored bita izgleda ovako: 87654321 65432187 87654321 H S C |
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