1. The L293D chip is a type of H-bridge. 2. Can drive 4 DC motors or 2 stepper motors or 2 servos . 3. Up to 2 stepper motors with single coil, double coil or interleaved stepping. 4. Pull down resistors keep motors disabled during power-up. 5. 2 external terminal power interfaces, separate logic / motor supplies. 6. Compatible with Arduino Mega, Diecimila, and Duemilanove. 7. The mark on the board may different due to the craftsmanship.
