Nuprl is designed to run on a terminal with an ordinary keyboard with a control key, a keypad with nine keys arranged as in figure and, optionally, a mouse. In the subsequent discussion we shall assume that these are available, and we shall assume that the mouse comes with three buttons called L, M and R (for left, middle and right, respectively) and is activated by clicking one of these buttons. However, one may simulate moving the mouse by using the keypad as follows. The arrow keys are used to move the cursor; if the arrow keys are used alone then the cursor moves in the direction of the arrow by either a single character or a single line. The cursor can be made to move in larger steps by pressing the key LONG LONG } before the arrow key. The COMMAND COMMAND } key is used for returning to the command window momentarily while in the middle of editing. For any particular terminal one may have to simulate the keypad and/or the mouse on the keyboard using control keys in combination with ordinary keys.
Figure: The Keypad
DIAG } }JUMP } }LONG } }SEL } }MOUSE }
The mouse is used for moving the cursor on the screen, for opening windows and for moving windows. An arrow on the screen called the mouse cursor responds directly to movements of the mouse. We shall also have occasion to refer to the cursor which responds to the keyboard and keypad commands as the cursor . To move the cursor, one places the mouse cursor at the desired position and clicks button R.