When you haven't done anything before with a microcontroller, I wouldn't start with a C program for my first efffort. Drop down into assembler and write a quick and dirty routine that can bit bang all the pins of one port in sequence.

Don't forget to jump over the interrupt vectors, don't forget to set the stack location. The rest is easy.

When that works, yuo have verified that your hardware is talking to you. Keep the "sanity check eprom" safe. When your system stops working, and you can't decide whether its your code or hardware, put the sanity rom back in. If it doesn't work, get some coffee, calm down and start again. I have a sanity check eprom which checks the serial port too, it transmits the classic Hello World if its OK.


Steve