LED-based moving-message displays are becoming popular for transmitting information to large groups of people quickly. These can be used indoors or outdoors. We -hotels, training institutes, nightclubs and shops.
Compared to LEDs, liquid-crystal displays (LCDs) are easy to interface with a microcontroller for display-ing information as these have many built-in functions. But these can't be observed from a distance and large-size LCDs are very costly.
LED-based displays can be of two types: dot-matrix and segmental. If you implement a moving-message display with multiplexed dot-matrix LEDs, it will be very costly for displaying 16 characters or more at a time.
Moreover, programming will require a lot of data memory or program memory space. An external RAM may be needed to complement a microcontroller likeAT89C51.