Yes it will,,,,,,,but please read the section of the the 8051 family users guide that discusses the operation of I/O pins on 8051 architecture parts. This discussion on I/O pin direction comes up a lot and it is best for you to become very familiar with how the pins work if you intend to use this type of processor. Here is a link to a the document I mention.

http://www.semiconductors.philips.com/acrobat/v...WARE_1.pdf

The discussion of how ports on '51s work starts on page 2.

Michael Karas