I have an atmel 89c51rd2 dil uP and have built it into a circuit with a 20MHz crystal rs232 interface and screw terminals at the IO (circuit is from phillips but matches the one's I have found on the web), using atmels Flip ISP i can communicate with the chip (sometimes!) and can sucessfully verify it.

The two main problems are that getting the flip program to sync is a very 'hit and miss' affair, but the main problem is that although i can download a program all of the ports remain unresponsive and the whole of p0 and p2 sit at around 2.3V (the other two sit at 4.7V..... I can see no reason for this and after trying another chip with the same results am completely lost please help!

Does anyone have any ideas, am i misisng a setting in the uP? what is going on?