ES 89c51 url's

Google search 89c51 pin diagram

http://chaokhun.kmitl.ac.th/~kswichit/easy2/easy2.htm

http://www.geocities.com/patelbaroda/MicroProjectBoards.htm

http://www.qsl.net/ok2xdx/Altimeter/altimeter.html


Google search serial port pin diagram

http://www.geocities.com/SiliconValley/Heights/5704/serial1.html
http://www.arcelect.com/rs232.htm