Hi John, thanks for your reply, I'll have a look at it when I get a chance - my father in law died about an hour ago, so suddenly, this isn't important for a while. :-(
>> Remember: programmers (usually) count from zero! I remember, I was once a programmer :-) >> So in your example, the first map entry is actually pointing to the >> second map entry and so on. Ok, 0->1->2->3 but when we get to C->D->E->F->$0000. What's going on here? Is this sequence telling me that the map groups (of 4 sectors each) 0 through $F are all linked in a chain belonging to whichever file has file_id 1 and that block group $10 is the final one in the file? If so, yippee! If not, boo hiss! >> This would suggest that the entry for the first free group is >> pointing to that of the next free group... I don't follow you here. According to the header fields, the first free block is $338F and not the zero'th block in the map. Unless you mean block $338f and not block zero of course, as the first free block. >> The directory entry for a file should give you the number of its >> first group. >> Since group_num * sectors_per_group = sector_number on disk >> the directory starts at sector $10 * 4 = $40. Assuming the root directory is file zero, this would be why we need to have it listed somewhere as otherwise it would start at sector zero on the disc. I assume that then that the directory entry for the root directory is all zeros then? This seems to be the case with my example file so far. Ok, A little clearer now, I notice that we have an incrementing word in the directory entry at offset $3a in the directory entry. This is new (to me anyway) but explains how to get from a directory entry to a map block and hopefully, from there to a sector. >> Have fun! I will at some point in the future, but fun is unfortunately not on the agenda for a while. :-( I appreciate your taking the time to explain these things to me, one last question for now. Where did you find out? Cheers, Norman. _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
