Hi,
This is actually my first time posting here.
I'm a Computer Engineering student and I was given a few DS89c420 MCUs from Maxim. I've read through the data sheets and have tried a few different things to see if they are working. But it acts very strange to everything I do.

First I tried connecting an LCD to it using the tutorial on this site, I got the code assembled and transfered to the unit without any problems (its flash ram, with builtin bootstrap) but the LCD displays random stuff, if at all!

Then I tried just connecting a couple LEDs to a couple port pins and turning them on.. but it doesn't really work! sometimes they flicker, other times they are on, or off. very strange!

Is there a simple test I can do? maybe light up a few LEDs when it starts?
If you're not familiar with the 89c420, its 100% pin and instruction compatible with all the other 8051s.

Like I said, I'm a beginner to the 8051, but have some knowledge of assembly. If anyone could give me any help in how to test these, it'd be trully appreciated!

Thanks!