That was my 1st thought. Traditionally the mul CPU instruction uses two registers for the result, as the expectation is that it overflows. Add/sub needs only a

That was my 1st thought. Traditionally the mul CPU instruction uses two registers for the result, as the expectation is that it overflows. Add/sub needs only a single overflow/signed flag. OTOH, it's 64bit and only unsigned, so yeah 64 bit gotta be enough for everyone (unlike 640KB mem)?