CD74HC4067 Multiplexor. Is Resistor important?

hi everyone

just a quick question, specifically about a multiplexer but may just be a 'rule of thumb' for many ICs

with the CD74HC4067E PDIP

Ive got a 100nF cap accross the power

but do i need a resistor along the 'enable pin to ground' connection

the schematic on the single SMD CD74HC4067 board here: http://www.sparkfun.com/products/9056 has a 10k resistor

but the same chips here on a 3 chip board dont: http://mayhewlabs.com/products/arduino-mux-shield

is this resistor important??

tried searching and people mention building your own mux ect but no specifics on the resistor

thanks everyone

Logic chips like this can have the pins directly connected to either voltage rail. However a 10K to ground makes it look like a logic zero but allows you to easily pull it high later if you want to connect a signal to it.

Thanks! so I know its not essential, I’m just going to connect them direct to ground for now, as thats ok

but if I decide I want to enable/disable the chips for some reason, I add a resistor to ground ( is 10k enough for two chips?) so its enabled by default but use a 5v 'digital out pin to ‘HIGH’ to this enable wire to dissable the chips?

have i got that right?

Yes that is right. :)

( is 10k enough for two chips?)

Well if it was me I would use 1K resistors to pull down.