The Claris CAD manual and packaging both state that a hard drive is required to use Claris CAD. However, it is possible to install Claris CAD 1.0 on a high density floppy and use the HD floppy to run the program.
High Density floppies work only with computers that have the SuperDrive (FDHD) floppy disk drive installed. This includes the following Macintosh models: SE/30, IIcx, IIci, IIfx.