for debugging:
void Crash(void)
{ // always set a breakpoint here
// look at *SP to see where crash happened
}

for products with a display
Crash:
pop acc
pop b
push b
push acc
;routine to display 'error at (hex contents of a and b)
reti

for some products w/o display
void Crash(void)
{ 
for (;;;);//make watchdog bite
}