After porting mon51 to my target and performing several preliminary tests I noticed two strange facts: a) apparently there are four bytes on the DATA area that are corrupted: two of them seem to have the dptr contents and the other two point to the word following the last instruction of the module. Even the startup code doesn't clean them up. b) using timer 0 doesn't work as expected: it seems that the simulator does not stop the timer during its housekeeping tasks when running step-by-step. All tests run correctely after a 'go' or on a breakpoint-by-breakpoint basis. Does anyone have a clue on whats going wrong here? I am missing some obvious point? Tools: uVision 1.24; d-Scope 1.3w; Compiler 5.2; Monitor Driver 1.8 Target: plain 31, 8k RAM at 0x0000 von neumann, 8k ROM hw switched to 0x8000 after power-up