Showing changes from revision #2 to #3:
Added | Removed | Changed
Offset | 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 |
+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 |
+9 | Nzones | Number of zones in the map |
+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 |
+16-1F | Disc_Name | Disc name (spaced to 10 chars, no terminator) |
+20-23 | Disctype | Filetype given to disc |
+24-3F | Reserved, must be 0 |
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 |
# | 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) |
There are two different FileCore Disc descriptor formats. The earlier version only supports small hard discs, while the later version supports larger discs.
1 Small disc are returned on versions prior to RISC OS 3.60
2 Large discs are returned on RISC OS 3.60 and later