CMOS (4000 series) General Characteristics
* Supply: 3 to 15V, small fluctuations are tolerated.
* Inputs have very high impedance (resistance), this is good because it means they will not affect the part of the circuit where they are connected. However, it also means that unconnected inputs can easily pick up electrical noise and rapidly change between high and low states in an unpredictable way. This is likely to make the chip behave erratically and it will significantly increase the supply current. To prevent problems all unused inputs MUST be connected to the supply (either +Vs or 0V), this applies even if that part of the chip is not being used in the circuit!
* Outputs can sink and source only about 1mA if you wish to maintain the correct output voltage to drive CMOS inputs. If there is no need to drive any inputs the maximum current is about 5mA with a 6V supply, or 10mA with a 9V supply (just enough to light an LED). To switch larger currents you can connect a transistor.
* Fan-out: one output can drive up to 50 inputs.
* Gate propagation time: typically 30ns for a signal to travel through a gate with a 9V supply, it takes a longer time at lower supply voltages.
* Frequency: up to 1MHz, above that the 74 series is a better choice.
* Power consumption (of the chip itself) is very low, a few µW. It is much greater at high frequencies, a few mW at 1MHz for example.
74LS series TTL Characteristics:
* Supply: 5V ±0.25V, it must be very smooth, a regulated supply is best. In addition to the normal supply smoothing, a 0.1µF capacitor should be connected across the supply near the chip to remove the 'spikes' generated as it switches state, one capacitor is needed for every 4 chips.
* Inputs 'float' high to logic 1 if unconnected, but do not rely on this in a permanent (soldered) circuit because the inputs may pick up electrical noise. 1mA must be drawn out to hold inputs at logic 0. In a permanent circuit it is wise to connect any unused inputs to +Vs to ensure good immunity to noise.
* Outputs can sink up to 16mA (enough to light an LED), but they can source only about 2mA. To switch larger currents you can connect a transistor.
* Fan-out: one output can drive up to 10 74LS inputs, but many more 74HCT inputs.
* Gate propagation time: about 10ns for a signal to travel through a gate.
* Frequency: up to about 35MHz (under the right conditions).
* Power consumption (of the chip itself) is a few mW.
Edit: It should be noted that I got my information nearly verbatim from the Kelsey Park School Electronics Club website. It contains a nice wealth of information in a format easily assimilated.