Level 4 provides the full range of Robolab programming function including the use of variables and communication beyween RCX bricks.
The level 4 palette is mainly the same as level 3. The yellow stop symbol causes outputs to be 'floated' so motors are not braked but roll on until they stop. The output symbol with a question mark allows greater control over changes in speed and direction.
The musical tone icon can be used with a modifier to add one of 6 alternative sounds: 1=key click, 2=beep, 3=descending sweep, 4=rising sweep, 5=buzz, 6=fast rising sweep.
The main differences between levels 3 and 4 is in the extensions palettes at the bottom of the main palette. The Wait and Inputs palette includes some familiar items and also some new ones. Level 4 includes icons for the temperature sensor and also for the angle sensor, should you have either of these. The angle sensor can be used in conjunction with a motor to provide control over movement by measuring part-rotations in units of one sixteenth of a turn (360/16 degrees).
The container (jar) with a question mark is used with modifiers to wait until the value inside it reaches the value specified. The modifiers palette includes a number of containers (red, blue and yellow), which can be wired to the icon in the inputs palette, along with a numeric modifier that sets the specified value.
Level 4 includes a palette to reset sensors and other items:
