Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!sun!pitstop!sundc!seismo!uunet!microsoft!brianw From: brianw@microsoft.UUCP (Brian Willoughby) Newsgroups: comp.sys.apple Subject: Re: Usabale blocks on ProDOS data disk Summary: Tricks with DOS and ProDOS directorys Message-ID: <673@microsoft.UUCP> Date: 16 Feb 89 04:03:16 GMT References: <6631.23F858E1@cmhgate.FIDONET.ORG> Organization: Microsoft Corp., Redmond WA Lines: 31 In article <6631.23F858E1@cmhgate.FIDONET.ORG>, Jerry.Kindall@f10.n226.z1.FIDONET.ORG (Jerry Kindall) writes: > If you can shorten the volume directory, can you lengthen it? Sounds > reasonable, but it might meet up with some problems. > By carefully reading _Beneath Apple DOS_ or _Beneath Apple ProDOS_ as appropriate, you find that each directory can be extended or shortened by sector-editing the pointers to "next sector/block" to point to whatever sector or block you want. The only problems that I have had is that 3rd party disk programs (like Copy II Plus) don't fully interpret what is written on the disk. This causes certain files to be inaccessable, or the offending program refuses to use the space you have freed for file storage. Where DOS correctly follows the sector pointers, other software 'assumes' the catalog is in the standard location and gets lost. The problem with 3rd party software not performing to Apple scecifications is also true of the 40-track extensions to either DOS that have been mentioned. I use 40-track DOS and ProDOS disks regularly, because it's worth the added space, to (%,, with the 3rd party disk junk.. BTW, I have only had problems with the extra 5 tracks of a 40-track disk with one brand of disk. The DISK II formatting scheme utilizes a floppy somewhere between single and double densitys (FM or MFM) by using the Woz Group Encoding. Does anyone know if the data on tracks 35-39, because of the smaller diameter of the disk, is actually written at a higher density than some diskettes can handle? I always use Double-Density, and I would assume that this density could handle the slightly higher data rate if and only if the disks were *true* double density. Brian Willoughby microsoft!brianw #include