DMS is BUGGY!
OK guys, let me add my 2c to this discussion. Firstly I would like to say that every single version of DMS I have seen is bugged:
- Some games will apparently READ correctly, produce a DMS file. When you DMS TEST NameOfGame.dms it says no problem found. Then you unpack it and it says CRC error and aborts. Lame.
- Most versions of DMS have the CMODE options stuffed. If you choose CMODE HEAVY1 for example it will either crash or say that isn't supported (most versions, not all).
- Some games will apparently READ correctly, but if you convert the DMS file back to ADF and compare with the original, the files are DIFFERENT! This is not due to a dodgy disk as I have tested lots of these with FMS devices which cannot have errors. An example of this is Superfrog disk 3 cracked by Crystal. With one of the standard compression options (can't remember which) you cannot DMS the disk and get the same data as the crack. Usually I have found the final few tradks contain byte differences (track 78-79 usually).
In DMS' defence:
- It is the only format which allows you to distribute patches, a trainer or AGA fix of a couple of tracks.
- It compresses the tracks so even A500 owners without much memory can use it.
- DMS tools like DMSSplit exist to put a large 900k DMS archive into 2 pieces to give to your poor HD-less A500 owners.
- It is from the old scene days!
Now I will say that my entire collection of disk images are all stored in DMS format. Why? Purely because that is what the collection started off as and I can distribute patches/AGA fixes in that format. The main reason though is I can guarantee my DMS archives are 100% perfect.
If I want to convert any ADF file or floppy disk to DMS, I use DIC to read the disk as an ADF file. Then I use a utility I wrote to unpack the ADF to FF0:, run DMS to pack the archive, then it calls DiskWiz to unpack the FF0: archive back to an ADF and compares with the original ADF:
- If it matches, it deletes the original ADF and I have a 100% guaranteed exact duplicate DMS archive of the disk in place of the ADF. This is 100% safe as it has been unpacked by DiskWiz and matches byte for byte the original ADF.
- If it fails, it prints out an error message and cleans up the files LEAVING the original ADF so I know that wouldn't convert safely.
If anyone is interested in this utility I will try and clean it up (it's a bit messy) but it works for me and I can personally attest to having seen at least 20 disks in my time which DMS thought were good. In the old days I would now have a corrupt DMS archive and think that the game may have been a dud crack or missing features etc...
So there you go, DMS is bugged (but I still use it!)
PS: I request all original suppliers to avoid DMS when sending me stuff as the time to make an ADF and LHA/LZX it is usually faster, compresses better and I can be safe knowing that the ADF is 100% ok.
PPS: I find all emulators are crap at handling DMS archives anyway, they fire up XDMS to unpack it and then it doesn't put the unpacked ADF into the floppy drive anyway! What am I doing wrong?