Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!tut.cis.ohio-state.edu!ucbvax!MRCNEXT.CSO.UIUC.EDU!alfter From: alfter@MRCNEXT.CSO.UIUC.EDU (Scott Alfter) Newsgroups: comp.sys.apple2 Subject: Re: DOS 3.3 Question Message-ID: <9004091826.AA14659@mrcnext.cso.uiuc.edu> Date: 9 Apr 90 18:26:29 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 36 toddpw@tybalt.caltech.edu (Todd P. Whitesel) writes: ------------------------------------start------------------------------------ But it is for that reason that data is never stored closer than 3/4 of a track apart, and since 1/4 tracks are a pain to work with (you have to do gross things with the stepper magnets) DOS only uses full tracks to store data. Spiral tracking copy protection schemes use quarter tracks but spiral it such that data is never closer than 3/4 track at any point on the disk (assuming they are reading real data and not checking for the presence of intentional errors). ------------------------------------end------------------------------------- So what you're saying is that disk space isn't currently being as efficiently used as it could? I'm forever seeking ways to jam more than 140K on a disk. Apple's newer drives (DuoDisk, Apple 5.25, IIc internal) are supposed to handle 38 tracks with no problem (I have a DuoDisk), and the Disk II (and most of the drives modeled after it) are supposed to take a full 40 tracks. Why settle on a piddly 140K when you can get 152K? Your comment raises another possibility, though. If three-fourths of a track is a safe spacing, then even on the newer drives it should be possible to get 50 of the 3/4-tracks, for 200K on a side! Biggest problem here is that while you only have to poke one byte and fix the volume bitmap to get ProDOS to accept more than 35 tracks, it would take a major MLI hack to deliver 200K--not to mention that it would probably end up breaking the current format unless there's room for almost a whole new driver in ProDOS 8, and a way to distinguish between the "extended" disks and normal disks. (Anyone at Apple care to comment on this?) Besides, I can't figure out how to get anything less than half-tracks; you say quarter-tracks are a mess to get from the drive. Just what is involved in quarter-tracking? I have some material on how 5.25" drives work (including Beneath Apple ProDOS), but their documentation would have you believe that only half-tracks are normally possible. (I have seen quarter-tracks in copy programs, though.) Scott Alfter------------------------------------------------------------------- Internet: alfter@mrcnext.cso.uiuc.edu _/_ Apple II: the power to be your best! cs122aw@ux1.cso.uiuc.edu / v \ saa33413@uxa.cso.uiuc.edu ( ( A keyboard--how quaint! Bitnet: free0066@uiucvmd.bitnet \_^_/ --M. Scott, STIV