h6. [[FileCore]] h6(. » [[FileCore Technical Details|Technical Details]] h6((. » FileCore Disc Record Large h2. FileCore Disc Large h4(#disc_descriptor_large). File Disc Descriptor (Large Disc[2]) |_<^{width:4em}. Offset|_<^{width:8em}. Name|_<^. Meaning| |>^. +0|<^. _Log2Secsize_|<^. Log2 of sector size (Sector size = 2^x)| |>^. +1|<^. _Secspertrack_|<^. Number of sectors per track| |>^. +2|<^. _Heads_|<^. Number of disc heads, if interleaved otherwise -1 (1 for old directories)| |>^. +3|<^. _Density_|<^. "Disc density":#disc_densities| |>^. +4|<^. _IDlen_|<^. Length of id field of a map fragment (in bits)| |>^. +5|<^. _Log2Bpmp_|<^. Log2 of number of bytes per map bits| |>^. +6|<^. _Skew_|<^. Track to track sector skew for random access file allocation| |>^. +7|<^. _Bootoption_|<^. Boot option (as in [[*Opt 4]],n)| |>^. +8|<^. _Lowsector_|<^. Lowest numbered sector + "disc description flags":#disc_description| |>^. +9|<^. _Nzones_lsb_|<^. Number of zones in the map (LSB)| |>^. +A-B|<^. __Zone_Spare__|<^. Number of non-allocation bits between zones| |>^. +C-F|<^. _Root_|<^. Disc address of root directory| |>^. +10-13|<^. __Disc_Size__|<^. Disc size in bytes| |>^. +14-15|<^. __Disc_Id__|<^. [[Disc Cycle ID|Disc cycle ID]]| |>^. +16-1F|<^. __Disc_Name__|<^. Disc name (spaced to 10 chars, no terminator)| |>^. +20-23|<^. _Disctype_|<^. [[File Types|Filetype given to disc]]| |>^. +24-27|<^. __Disc_size2__|<^. High word of disc size| |>^. +28|<^. __Share_size__|<^. "Share Size Information":#share_size| |>^. +29|<^. __Big_flag__|<^. "Big Flag":#big_flag| |>^. +2A|<^. _Nzones_msb_|<^. Number of zones in the map (MSB) | |>^. +2B|<^. |<^. Reserved, must be 0| |>^. +2C-2F|<^. __Format version__|<^. "Disc Format version":#format_version| |>^. +30|<^. __Root size__|<^. Size of the root directory[3]| |>^. +34-3F|<^. |<^. Reserved, must be 0| h4(#disc_description). Disc Description Flags |_<^{width:4em}. Bits|_<^. Meaning| |<^. 0 - 5|<^. Lowest numbered sector id on a track| |<^. 6|<^. Treat sides as a sequence (not interleaved), if set| |<^. 7|<^. Disc is 40 track, if set| h4(#share_size). Share Size Information |_<^{width:4em}. Bits|_<^. Meaning| |<^. 0 - 3|<^. Log2 share size granularity (in sectors)| |<^. 4 - 7|<^. Reserved, must be zero| h4(#big_flag). Big Flag |_<^{width:4em}. Bits|_<^. Meaning| |<^. 0|<^. Identified as 'Large' disc, if set| |<^. 1 - 7|<^. Reserved, must be zero| h4(#disc_densities). Disc Densities |_<^{width:4em}. #|_<^. Meaning| |<^. 0|<^. Hard disc| |<^. 1|<^. Single density (125 Kbps FM)| |<^. 2|<^. Double density (250 kbps FM)| |<^. 3|<^. Double density (300 kbps FM), i.e. higher rotation speed DD| |<^. 4|<^. Quad density (500 kbps FM)| |<^. 8|<^. Octal density (1000 kbps FM)| h4(#format_version). Disc Format version |_<^{width:4em}. #|_<^. Meaning| |<^. 0|<^. Small directories| |<^. 1|<^. Extended (aka "+") with big directories| h4. Notes There are two different FileCore Disc descriptor formats. The earlier version only supports small hard discs, while the later version supports larger discs. fn1. [[FileCore Disc Record Small|Small]] disc are returned on versions prior to RISC OS 3.60 fn2. Large discs are returned on RISC OS 3.60 and later fn3. Valid in the "Disc Format version":#format_version is Extended, 0 otherwise h4. See also * [[Disc Cycle ID]] * [[FileCore]] * [[File Types]] * [[FileCore Disc Record Small]]