It seems that latest RVMK ARM v3.01a has problem to talk to Proteus VSM, I did not have problem using v3.00. Following are error message from uVision: Load "D:\\Program Files\\Labcenter Electronics\\Proteus 6 Demonstration\\SAMPLES\\GNU Chess\\gnuchess.ELF" *** Invalid Line Number Table ! *** Invalid Line Number Table ! *** Invalid Line Number Table ! Any experience and solution? Thanks. JSL