Some of the Amstrads shipped with either a 3"
or 2 1/2" drive. Don't
remember which, it's been a long times since I've seen one.
Most Z80-based Amstrads (CPC664. CPC6128, PCW8256, Spectrum +3) along
with the Tatung Einstein and Oric used a 3" drive. I've seen this drive
sold as an add-on for things like the BBC micro
-tony