The Grappler Card is a parallel printer card. Typing "PR #[slot the card is in]" will cause it to not give a prompt because all commands are now going to the printer and not the screen. Typing "PR #0" should return it back to the screen. This is true with all printer cards - parallel and serial. Only real way to test it is to have a printer attached to the card, but if it goes out and back with the PR Command, it should be working fine. The rest is configuring the card to meet the printer's options with dip-switches on it.

If I remember correctly, the C\PM Boot disk needs to be formatted in Apple DOS 3 or 3.3. It wont work in ProDOS. The other disks needs to be formatted in C\PM. You will need the 16K Language card in the Apple II/II+ for a full 64K.