During the 1980's the Western Digital floppy controllers were abundant. Starting with the 179x series and 279x ones after that. There were also more compact solutions like the 177x series which were popular due to the low supporting chip count. Like many I used all of these and learned to live with them. Especially the requirement to not poll their status too quickly was a nuisance. 

With that in mind I made two different designs of the IDE interface. One with a WD2793 and one with a newer WD37C65 device. The latter one is a NEC uP765 like interface plus some extra support so that it is a one chip solution. Both should allow reading of both 8" and 5.25" disks but the WD37C65 goes further (3" extra density) so an interesting option to explore. A 3D KiCAD representation of the WD37C65 version is uploaded to the picture gallery.

I have an old Siemens 8" drive which is well preserved and some original TSC FLEX OS 8" floppies (!) and it will be fun to see if I can read these eventually.

OS-9 drivers for the WD279x are around and should be easy to adapt. However, for a multi-tasking system these can be a drag since byte don't come out as a stream of bytes that can be transferred as a burst DMA. Instead people have used 'cycle stealing' DMA something which requires some overhead in managing.

So during design time I thought of a way to buffer the bytes from/to floppy drives sector by sector. Hence by keeping a 256-byte buffer between the CPU and the floppy drive, the sequence of writing/reading to/from floppy drives becomes much like interfacing to IDE disks and we can employ burst DMA transfer of data.

There is still the issue of how to deal with disk formatting which requires more than 256-bytes but it should be simple to create a bypass to the sector buffer and handle these the 'old way'.