As I recall it Zmodem was more than nominally faster than Xmodem but in those days to squeeze even 5 to 10% speed improvement in speed on a 2400-14400 bps modem

As I recall it Zmodem was more than nominally faster than Xmodem but in those days to squeeze even 5 to 10% speed improvement in speed on a 2400-14400 bps modem was huge.