Sorry,
I said that I cannot visit that site because of the firewall (the firewall of vietnamese net).
So if you can, you may download the site and send it to me via email.
doanhiep@swissinfo.org
For more information about pics and tutorial of PICs, you may see the signature of Nigel. He writes a very very very good tutorial with basic pics : 16f628 and 16f877.
Yeah, you only need pull up resistors on port0 of 89C51. The 3 other ports do not need pull up resistors.
In some case, 89C51 is simplier than PICs, because you don't have to write start codes to begin programming on 89c51. And the i/o can be use as i/o at any time. but with PIC you have to configure it before using.
If you see in the scheme, they connect the pins directly to RB of P16f84, you can do so to 89c51. with port1, and port2. Port3 is usually used for special functions, but you may use it as i/o port in other applications.
16f84 has only 18pins, but your 8951 have 40 pins. And in this case, your 8951 stronger than 16f84, you don't have to worry muchie.
So, if you need a pcb, copy the site and send it to me. I'll make it for you.
I'll reply to you in .pdf format, so that you can view and print it to build your pcb.
Goodluck.