The TEAC FD-505 is a combination high-density 5.25-inch drive and 3.5-inch floppy drive, in a half-height form factor. I have one and wanted to use it for floppy drive imaging with a Greaseweazle. This is trivial to hook up, using the default jumper settings, and selecting each drive using the --drive A or --drive B Greaseweazle options.
However, I want to add a third drive into the mix (a double-density 5.25-inch drive). Greaseweazle supports using three drives, but only as long as they can use "Shugart" style signaling.
The FD-505 doesn't have the "DS0, DS1, DS2" jumpers normally required for this. Because it has only a single 34-pin floppy connector, it also can't use the presence or absence of a twist to differentiate each drive. Instead it has a unique set of jumpers which can more or less recreate the cable twist on the control board.
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