Date: Fri, 30 Jan 1998 17:50:24 -0600 From: David Kelly <dkelly@hiwaay.net> To: Alan Batie <batie@aahz.jf.intel.com> Cc: hackers@FreeBSD.ORG Subject: Re: floppy media change detection Message-ID: <199801302350.RAA15921@nospam.hiwaay.net> In-Reply-To: Message from Alan Batie <batie@aahz.jf.intel.com> of "Thu, 29 Jan 1998 17:59:13 PST." <19980129175913.55683@aahz.jf.intel.com>
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Alan Batie writes: > Dating myself horribly, I seem to remember the days of 360K floppies > where in the dos world, you'd do yourself in bigtime by swapping floppies > and the directory would be cached and you'd end up writing the wrong > one back out. It seems like a few of the later 360's and then the 1.2's > and 1.44's fixed this with a media change signal of some sort (maybe it > was the transition from 180K to 360K?). Am I hallucinating? I don't > remember how you told dos you wanted to change the floppy certainly, so > it's possible... A quick scan through the fd controller doesn't indicate > any such thing, and it would be really handy for an application I'm > working on... Am I out of luck? Thanks... I think the *really* old stuff optionally had a signal that would inform the controller if the door was open. Think there were options to lock the drive door shut from the controller too. Cheap systems such as PC's never implemented it. Some CP/M systems did. Apple went one further on the Mac with motorized eject, so the user couldn't get the floppy out without permission of the OS. Also think PC's ignore the high density hole in 1.44M floppies too. Macs do not. Really old floppy drives had a head load solenoid to remove the head(s) from the media. That was common on 8" drives where the spindle never quit. The last generation of 8" floppies could start/stop their spindle motor the same as most early 5-1/4" drives. Don't remember, but I believe the Zip disk on my PowerMac signals an eject request to the OS rather than immediately eject. And the same sort of thing happens (?) with FreeBSD and CDROMs. When mounted the CD is "locked" and the eject button doesn't work. -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system.
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