TEAC FD-55GFR = Quad Density?

A fair number of 55F's had head-load solenoids. 'Way back when PC-AT's and AT-clones had more-or-less standardized BIOS conventions, I wrote a little DOS TSR that would allow a 1.2M 5.25" to masquerade as a 3.5" 720K drive. It seemed silly not to take advantage of the native capabilities of the 5.25" drive and make the 720K 96 tpi possible on DSDD diskettes. Some "clone" BIOSes didn't require a special TSR to read 720K 5.25" diskettes, but the IBM PC-AT did. When the various clone makers started to reassign the meaning of the bits at 40:90 and 40:91, this scheme became broken and it was simpler to employ a device driver that manipulated the 765 directly. When we were devising forensics exercises for the law enforcement community in the early days, we used to pass out an exercise on a 360K diskette, with innocent decoy data written on the even-numbered tracks and a complete second 360K image with the incriminating evidence on the odd-numbered tracks. Somewhat OT: I find that commodity 1.44MB diskettes are far more reliable when used as DS2D media. Just cover over the "window" with some opaque tape or one of those "write protect" tabs from a box of 5.25" diskettes (or "write enable" tabs from a box of 8" diskettes). Sadly, although XP will read them, it will no longer format them. Time marches on... Cheers, Chuck