Hi - > I wrote some assembly programs to comunicate with the > UART1 and UART2 serial ports of SID. > I was surprised that i didn't need to initialize > serial port before send the data to it. What kind of initialization did you expect? I believe most SID components aim to start up in a state similar to powerup of the physical devices. However, since some features of the hardware may not be emulated, and others may be hidden by properties of the host I/O, you may get away with using initial state on the simulator. This is true in general with simulators: it is possible to get a "false positive" in the sense that a program may run on the sim but not on hardware. > Is it right that SID doesn't need any initialization > of its components before using them? Not really. What you're seeing is probably a coincidence. - FChE