With extremely long unshielded parallel cables you're going to tons of cross talk and other emissions that will cause bitflips / errors.
In addition at 33Mhz the speed would be (using speed of light instead of calculating velocity factors):
(the speed of light * 1) / (33 mhz) = 9.08461994 meters
per cycle, which isn't taking into account the capacitive load of the wire and registers at the other end (which will act as a big filter). You need to meet some sort of timing constraints in order to count for clock sync issues etc...
Modern CPUs can run faster since the capacitive load of a transistor is extremely small (since they're nanometers in size), plus the loop sizes of the interconnects are extremely small, lowering EMI emissions.
In addition at 33Mhz the speed would be (using speed of light instead of calculating velocity factors):
per cycle, which isn't taking into account the capacitive load of the wire and registers at the other end (which will act as a big filter). You need to meet some sort of timing constraints in order to count for clock sync issues etc...Modern CPUs can run faster since the capacitive load of a transistor is extremely small (since they're nanometers in size), plus the loop sizes of the interconnects are extremely small, lowering EMI emissions.