cds@duke.UUCP (Craig D. Singer) (06/26/86)
I have an interesting problem people might be curious about. I have an enhanced //e with 128k, and a DuoDisk in slot 6. Recently I purchased a program called Copy II+ which is a disk utility program with things like a sector editor, nibble editor, etc. Yes, I am using it to make archival backups of copy-protected disks, but that is not the issue here. If I take a disk I want to copy, say Apple Logo II or Music Construction Set, put it in Drive 2, and ask the sector editor to read an arbitrary track and sector, everything works fine. I know that the sector editor is working in drive 2 for several reasons, the most obvious of which is that when I read track 0, sector 0, and disassemble, I find precisely the boot code I expect to for that program. Now, if I take that same disk, put it in drive 1, and use the sector editor, the drive reads garbage. By garbage I mean totally unrelated bytes appear regardless of which track and sector I read, including tracks and sectors which were not written in a "funny" manner, i.e., normal DOS or ProDOS tracks. This doesn't just happen if I use the particular sequence of reading in drive 2 and then drive 1, mind you, but any time I read from drive 1. And the garbage I get, I might add, is consistent for a given track and sector. The bizarre thing is that drive 1 works perfectly fine for ordinary purposes. It boots disks, reads and writes track, files, directories, etc, according to any other program's wishes. It makes copies to drive 2 (using the ProDOS utilities) just fine. It formats fine. If I use the sector editor to make such copies, however, the data on the disk in drive 2 gets precisely the garbage read from drive 1. Furthermore, if I copy from 2 to 1, drive 1 writes garbage even though drive 2 reads correctly! A second reason I know drive 2 is working fine is that if I copy from drive 2 to drive 2 (a royal pain in a sector editor, since it does one track at a time) the copy is perfectly good. An interesting side effect is that copying from 2 to 1 leaves garbage on the disk in drive 1, but if I read that garbage using drive 1, it looks like the real thing! To the sector editor, that is, because if I then put that disk in drive 2 and use the sector editor to read it, it's garbage again. Likewise, it won't boot. I have checked and played with the drive speed to no avail, so I put it back to 200ms. Since the drive works fine for ordinary applications I cannot imagine that it is misaligned. And if you check through the code on the Copy II+ disk, you find that the drives are treated identically, so it doesn't seem possible that there could be a bug. Besides, such a severe bug in a product which has already sold umpteen million copies is rare. So what do you think? Can something else be wrong with the drive that only messes it up with respect to the code for the sector editor (which is, perhaps, very sensitive with respect to some factor(s))? Can something be wrong with the disk controller in slot 6 that would only affect one drive? I have not tried messing with the "parameters" in Copy II+ because the combinatorics are insane, and I have no idea why any of them should have to be changed to make one drive work when the other one works "as is." I have not tried the nibble editor or bit copier, but even if they work that does not explain away this problem. One interesting side effect: the way I copied Apple Logo II without going crazy doing disk swaps in drive 2 was to do a "regular" copy from drive 1 to drive 2 using Copy II+, which ignores the error you get on track 1 (the "protected" track), then use drive 2 to sector copy track 1 with special parameters (supplied with Copy II+). But when I read from drive 1 to drive 2 and got the error on track 1, drive 1 proceeded to get an error on every track thereafter. When I reversed the direction, drive 2 got the read error on track 1 but then copied the rest of the disk successfully! Even then, because I was using Copy II+ instead of the vanilla ProDos copier, the data written by drive 1 was junk. Fortunately, doing a regular copy with just one drive only takes two swaps, so I used drive 2 alone. A thousand kudos to anyone who understands the depths of disk drivery and/or Copy II+ and knows what in heck is going on here. -- Craig D. Singer, Dept. of Computer Science, Duke University Durham, NC 27706-2591. Phone (919) 684-5110 (ext.20) CSNET: cds@duke UUCP: ...!decvax!duke!cds ARPA: cds%duke@csnet-relay
ranger@ecsvax.UUCP (Rick N. Fincher) (06/27/86)
> I have an interesting problem people might be curious about. > > I have an enhanced //e with 128k, and a DuoDisk in slot 6. Recently I > purchased a program called Copy II+ which is a disk utility program with > things like a sector editor, nibble editor, etc. Yes, I am using it to make > archival backups of copy-protected disks, but that is not the issue here. > > If I take a disk I want to copy, say Apple Logo II or Music Construction > Set, put it in Drive 2, and ask the sector editor to read an arbitrary track > and sector, everything works fine. I know that the sector editor is working > in drive 2 for several reasons, the most obvious of which is that when I > read track 0, sector 0, and disassemble, I find precisely the boot code I > expect to for that program. copy ii+ is upgraded almost monthly, the prodos version is fairly new. version 6.6 is the most current one i know of. i had some problems with version 6.5, mostly when using an accelerator. duodisks are strange animals, i don't know enough about them to help there, but they do some funny things. rick rick@ncsuvm ranger@ecs