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Glossary of terms



Cluster    A group of sectors, and normally smallest amount of space a file can use, ie a 1 byte file will always take up 1 cluster of space on the hard drive.


Endian    Little and Big endian define how a computer stores its numbers. Any number over 255 requires more than one byte to store, and little and big endian refer to the sequence.  Little endian stores the lowest byte first, and big endian stores the highest byte first.  So if we want to store the value 266, this is 10AH.  In Little endian it would be stored   0A 01   and Big endian, it would be store 01 0A


           Little endian is also known as Intel byte ordering, and Big Endian as Motorola byte ordering.  It could also be PC and MAC)          


FAT        File allocation table - used on DOS/Windows systems to track which sectors have been written to

FAT12                12 bits per cluster, max 4096 clusters

FAT16                16 bits per cluster, max 65536 clusters

FAT32                32 bits per cluster, max 4G clusters 


GUID            Globally Universal ID         


MFT        Master File Table, file descriptions in NTFS.  A two sector record that always starts with the text FILE


MD5       16 byte hash value


SHA-1    20 byte hash value


Slack           Space at the end of a file, but contained within a cluster that has been used


Unallocated space  Complete clusters that are not used by current files