John Sawyer and Chuck Meyer of CJS Systems described this problem with Macintosh¿ 800K floppy drives during an eject, if the read/write heads are towards the outter edge of the diskette (which they typically are) they will every once in a while catch on the shutter door of the diskette and tear off as it is ejecting, permenantly damaging the drive. If you've ever had your drive suddenly refuse to recognize diskettes that it used to, and the person who fixed your drive had to replace it outright, there is a very good chance that this is what happened.
HOW IT SOLVES THE PROBLEM:
SafeEject attempts to remedy this problem by moving the read/write head to the center of the diskette, just before it is ejected. CJS Systems set up a diskette drive out of its case for me so I could watch this behavior. I have encountered no problems with the patch, and John Sawyer is confident that it will prevent the problem described above.
HOW TO USE IT:
Drag the SafeEject icon into the System Folder of your startup disk, and restart your computer. The SafeEject icon should appear on your screen during startup to let you know it has been installed. To prevent SafeEject from being loaded, hold the mouse button down during startup. No icon will appear. If you have any questions about how to use SafeEject, BMUG (the Berkeley Macintosh Users Group, 415/849-BMUG) has agreed to field those questions.
FOR THE TECHNICALLY MINDED:
SafeEject is an INIT which copies a small resident program (about 1K) into memory, then calls that resident program to install itself. Installation consists of patching the OS _Control Trap. The patch is aprolog patch which checks for the 'eject' control call, finds the drive in the VCB queue (failing that uses the other parameters passed it), checks for reference number -5 (the .SONY driver), attempts to read sector 409344 (will center the read/write heads on an unformatted or 400K formatted drive), and if no error is detected, will attempt to read sector 818688 (centering the heads on an 800K drive), and then jumps into the original trap. I am told that the FDHD drives automatically perform this 'park' function so I have not bothered to do a third read. SafeEject was written using Apple¿'s MPW 68000 Assembler.
LEGALESE:
SafeEject is free for noncomercial distibution, however I reserve all copyrights to the Source Code, Object Code, and Icon.
