Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!hc!lll-winken!uunet!snjsn1!bilbo!greg From: greg@bilbo (Greg Wageman) Newsgroups: comp.sys.atari.st Subject: Writing on write-protected disk confirmed Summary: I saw it happen Message-ID: <769@snjsn1.SJ.ATE.SLB.COM> Date: 23 Mar 89 17:42:53 GMT References: <1608@orion.cf.uci.edu> Sender: news@SJ.ATE.SLB.COM Reply-To: greg@sj.ate.slb.com (Greg Wageman) Organization: Schlumberger ATE, San Jose, CA Lines: 41 A while ago there was a posting stating that it is possible to write on a disk with the write-protect hole open (write-protected). Most of us were skeptical, wanting to see schematics to know if this was, in fact, possible. I have not seen any schematics, but I have witnessed, first-hand, a write-protected disk being altered by a program. The program is the Atari CP/M-Z80 emulator, which I downloaded from GEnie. I had write-protected the "system" disk to prevent mistakenly deleting files during a previous operation, and had forgotten to write-enable it again. I gave the CP/M "era" command to delete a file from the disk. The disk made some *very* unusual sounds, and I got an error from the emulator indicating that the disk was bad ("BDOS error on A: bad sector"). I tried again; same result. When I did a "dir", the file was gone. I removed the disk from the drive, to look at it, and was shocked to discover that even though it was still write-protected, the emulator had succeeded in deleting the file! Now, I don't claim to know at what level the CP/M emulator is driving the hardware. Since the CP/M emulator writes its own disk format, it's probably doing physical I/O via "rwabs" at least. It's possible that you can't get this behaviour through the normal TOS calls; I simply don't know for sure. I can tell you this, though: I'm going to be a lot more careful about what I do, even if the disk *is* write-protected. No smiley. Longish .signature follows. Skip now, or don't complain! Greg Wageman DOMAIN: greg@sj.ate.slb.com Schlumberger Technologies UUCP: ...!uunet!sjsca4!greg 1601 Technology Drive BIX: gwage San Jose, CA 95110-1397 CIS: 74016,352 (408) 437-5198 GEnie: G.WAGEMAN ------------------ There is only one "r" in "pejorative" ------------------ Opinions expressed herein are solely the responsibility of the author. (And the author wouldn't have it any other way.)