I'm not sure, but it looks like you want simulator, that is able not only to simulate SCI peripheral, but also allows you to send/receive from/to terminal window. CW for HC12, and even Coldfire debugger from CW for MCU's V6.3 allows this. But for some very weird reason terminal I/O is not possible in CW6.3 S08 debugger. You may try NoICE debugger (www.noicedebugger.com). It won't simulate timers and all other stuff, but serial I/O simulation to terminal window is available. It should be fine with SC4. As far as I know it doesn't support banked derivatives like QE128, D128 etc.