Hello, this is my first robot I have posted, but I have made lots more. This car measures the distance it travels in 5 to 10 seconds. There is a shaft encoder inside the front of the car. The shaft encoder uses a light sensor and a disk with black to white and white to black transitions. The measurement is about .04 millimeters off. I tried to make the car as small as possible. The program turns on the motors for 5 to 10 seconds. While that is going on the light sensor reads the disk. Then if the light sensor sees white it fills the red container with the number 1 and if it is not white it fills it with the number 0. After that it reads the disk again. Then if it is white it looks in the red container and if the value is 0 in it it adds 214 to the User1 container and sets the value to 1 in the red container. If the light sensor reads the disk and it is not white it looks in the red container value. If the value of the red container is 1 it adds 214 to the User1 container and fills the red container with 0. Then it sets the display on the RCX to the value of the User1 container with the decimal point moved 2 places across. This repeats until the 5 to 10 seconds is up. Then the top task forces an event, jumps to the event land, displays the value of the User1 container on the RCX for 2 seconds and ends the program.