CF2 Compact Floppy Disc
The 3" discs for the Amstrad Disk Drive are called CF2 (Compact Floppy Disc). CF2 discs were produced by AMSOFT, MAXELL, Schneider, Panasonic. In late eighties, cheaper Noname discs were also available (although these were rather unreliable).
Capacity is 180 Kbytes per side (the discs can be flipped to access the other side, giving a total of 360 Kbytes per disc).
