Connect to uLisp Linux with screen: screen /dev/ttyUSB0 115200 macOS with screen screen /dev/tty.usbserial-55D2D232BE 115200 Emacs (defun ulisp-terminal-start () (serial-term "/dev/ttyUSB0" 115200) (term-line-mode)) M-: (ulisp-terminal-start) Arduino software Tools -> Serial Monitor