This video shows 4 motors running using the Sainsmart Motor Drive Shield L293D with an Arduino Uno. I review the shield noting the PROs and CONs.
You can download the code here...
https://codebender.cc/user/fish
or here:
http://www.mediafire.com/file/m9q62uq...
To view more of my videos please search for "Scott Mon" on YouTube.