Turns out that when I ported my code to the 8051, I inserted a couple errors. I guess that in the future I should look harder for errors from myself rather than the compiler.

However, there was still one strange error, which I fixed and I don't know exactly why it worked. I guess it kind of has to do with how I found a "match"... I was using a "short" type to hold either the 1 or 0 that was to be output to the LED. In some situations this was fine, but in others, it would output a 0 when it should have been a 1. I changed the "short" to "char" and it works fine now. Strange!!... or maybe not so strange if you know why.

Thanks for the replies Andy.