8-) Winbackup seems quite a long time ago ;.) Cheers...Ralf
----- Original Message ----- From: "Norman Dunbar" Sent: Friday, April 25, 2008 8:52 PM Subject: Re: [Ql-Users] QXL.WIN internal format? > Evening John, > > Thanks for yet more explaining. I discovered (!) that if I take the > file_id from the file's entry in the directory and use that to index > into the block map (having subtracted 1 first) I get a 'value' which I > call stragely, the block number. > > Multiply that by the number of sectors per disc and we have a sector > number. > > Multiply that by 512 and we have the file's address in the hard disc. > > It appears that in QLWA formatted 'discs' there is a header of 64 bytes > at that address immediately followed by the first 2048-64 bytes of the > file. > > Progress! > > I haven't yet figured out where the second block of the file should be, > but I'll be looking at some point in the future.e > > I thought that the block number (also) pointed at the next block in the > chain but when I followed that logic, I found that the second block in > my test file was not in anyway connected to the first one. Needs more > investigation I think. > > >> Almost :-) >> The chain actually belongs to the header/map and map entry $F >> (containing $0000) is the last in the chain. > Hmmm, see above. This is where I seem to lose the plot. Are you saying > that the zero block in the map, holding $0001 is telling me (a) where on > disc to find the 4 sectors for this block PLUS (b) where the second > block in this file is (ie, map entry $0001). > > This is what I tried with my test file but got nowhere. :-( > >>> Unless you >>> mean block $338f and not block zero of course, as the first free >>> block. >> >> Yes: >> >> map_entry_for_first_free_group->map_entry_for_next_free_group->... > Ok, thanks. > > >> That's right - the file number is an index into the directory, not the >> map or the disk. > I was going to ask about sub-directories and adding/deleting files to > and from those but then I discovered that each entry in every directory > has a file_id word (implies 65536 maximum files per disc) at offset $3a > in the directory entry - which leads nicely into the block map and from > there to the first 4 sectors on disc. > >>> last question for now. Where did you find out? >> I could tell you but then I'd have to kill you :-) > Aha, that old one - I use it often myself at work. :-) > >> Actually, the scheme is basically the same as used by FAT-formatted PC >> disks. > Ok, thanks, I'll see what other info I can dig up on FAT discs sometime. > Might help! > >> The rest is just experience and a (little) bit of logic... > Ah well, experience is something I can look forward to, I only started > this yesterday! > > Thanks again. > > Cheers, > Norman. > > _______________________________________________ > QL-Users Mailing List > http://www.q-v-d.demon.co.uk/smsqe.htm _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
