> Just as an aside, I recently encountered a
datasheet for the WD 1773 FDC
> (similar to 1770/72). Do you know of any systems in which it was used?
No, they are not the same. the latter will do DD and the 1773 was single
density.
The 1773 was used on TRS80, Icom, and other early systems that were
softsector.
Allison