storew method
Implementation
void storew(int address, int value){
checkBounds(address);
checkBounds(address + 1);
if (value > 0xffff) {
throw GameException('word out of range');
}
if (value < 0){
//convert to zmachine 16-bit signed neg
value = MathHelper.dartSignedIntTo16BitSigned(value);
}
assert(value >= 0);
assert(((value >> 8) & 0xff) == (value >> 8));
memList[address] = value >> 8;
memList[address + 1] = value & 0xff;
}