*er...I don't remember (editors please ?)
*1,2 Mo was the maximum...on my old PC...
== Beware : HD ==
Nowaday, only HD 3"1/2 disk can be found at good old retailer's.
But or beloved CPC can't understand easily the concept of High Density Disk with 1,44Mo avalaible...
So you have to cheat : just put some duct-tape (scotch-tape, whatever...) on the HD Hole.
Tada, a proper DD disk with 720 Ko if your OS allows it.
Or a common 2x180Ko (2x 178Ko ?) with firmware Loco Basic, if you have a manual side switcher button too of course).
PC users used to do the opposite : file a HD hole on DD disk...this worked well sometimes.
== A clever choice ==