Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!snjsn1!bilbo!greg From: greg@bilbo (Greg Wageman) Newsgroups: comp.sys.atari.st Subject: Re: Writing on write-protected disk confirmed Message-ID: <804@snjsn1.SJ.ATE.SLB.COM> Date: 31 Mar 89 23:49:04 GMT References: <1608@orion.cf.uci.edu> <769@snjsn1.SJ.ATE.SLB.COM> <2481@netmbx.UUCP> Sender: news@SJ.ATE.SLB.COM Reply-To: greg@sj.ate.slb.com (Greg Wageman) Organization: Schlumberger ATE, San Jose, CA Lines: 46 In article <2481@netmbx.UUCP> hase@netmbx.UUCP (Hartmut Semken) writes: >In article <769@snjsn1.SJ.ATE.SLB.COM> greg@sj.ate.slb.com (Greg Wageman) writes: >>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. > >Whether this is possible or nor depends on the drive used. > >My Teac FD55F and Mitsumi 3.5 inch floppy do not write to >write-protected disks. > >If I disconnect the -WR line from the drives to the ST and pull it up >(10kOhms to +5Volts) on the ST side, the ST 'writes' to the disk, but >rereading it displays an unchanged directory. Nothing really gets >written. > >The read/write amplifier in the Teac is disabled by the internal >WriteProtect signal. So it is not possible to write to write protected >disks. > >Some NEC 1036 and 1037 do write to writeprotected disks (confirmed); >my Aplle Disk ][ (with an Apple ][) does the same... Yup, this is correct. What fooled me was that the OS altered the *cache*, and when the write to the disk failed, it didn't re-read the disk and update the cache. A subsequent 'dir' command displayed the (erroneous) cache data. The file would have reappeared after a forced media change. Sorry about that. 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.)