UOSFS Root Store Layout

A store that has been initialized to hold a UOS File System has a structure that allows UOS to locate information about the store, the file system, and where to find the location of the root of all files stored in the file system.

type FS_Boot_Record = packed record

                         Bootstrap1 : array[ 0..15 ] of byte ;

                         Header : int64 ;

                     end ;

    FS_Header = packed record

                    ID : smallint ;

                    ID1 : byte ;

                    Version : byte ;

                    AT_Offset : int64 ;

                    AT_Size : int64 ;

                    Flags : int64 ;

                    Clustersize : cardinal ;

                    Folder_Clustersize : cardinal ;

                    Root : int64 ;

                    Volume_Label : string[ 127 ] ;

                    Password : string[ 31 ] ;

                          OS_Position : int64 ;

                          OS_Length : cardinal ;

                          MMC_Position : int64 ;

                          MMC_Length : cardinal ;

                          HMC_Position : int64 ;

                          HMC_Length : cardinal ;

                end ;

The first cluster on a store contains the boot block, which is the bootstrap program for the store.  The first 16 bytes are reserved for the bootstrap, followed by an 8-byte pointer to the file system header, and then followed by the rest of the bootstrap code.

The File System header contains the size and location of the store's allocation table, information on the cluster sizes, flags, the location of the root folder, and other information.