I think you are going to give yourself a whole lot of extra work building up a circuit using all these chips. There is no reason to any longer build an 8051 type setup with external components like shown in the circuits you linked to. In particular this 8255 chip is an outmoded piece of garbage which will soon be the dust of history. You would be far better off using a chip with on-board FLASH. RAM, and A/D converter. You can buy this simple development kit (it has a space on the side where you can install I/O buffer components if needed. Here is a link to the development kit:

http://www.silabs.com/products/...F226DK.asp

To see how much simpler this method is please consult the schematic on page 9 of this document:

http://www.silabs.com/products/pdf/an177rev0_3.pdf

I have linked you to a nice little chip family which is perfect for small projects. If you need more capability going forward the same company has a multitude of parts that offer performance up to 100 MHz 1X clocking, 128K bytes of FLASH, 8K onboard RAM, USB, CAN, D/A, comparators etc etc all built on board.

Michael Karas