I have used this small program during Christmas holidays to have some blinking tree. I've used EBCS 68HC11 board (SCz board).
The program controls an IO port and makes that port blink at various speeds. The IO port is the port A, bit 5 (or 6). That port directly controls a triac via an optocoupler (MOC3041). You can check this bootstrap program by connecting a led on bit 5 or 6 of port A.
Implementation Notes:
_start
function must be at beginning of this file. By doing so, it will be mapped at address 0 by the linker and we avoid to have some jump to call it (since the boot will jump there)._start
function. We don't care because this clobbers some initialisation part.