Thanks, this helped a lot.

The offending code, which works fine is.....
LRC = 256 - LRC

LRC is defined as a byte, but I have to subtract LRC from $100
I guess I could say....
LRC = $FF - LRC
LRC = LRC -1

Would be the same thing..., unless there is a better way or I just need to ignore the error since we only need the 8 LSB anyway.

Richard