Hi
I want to use the 3-line to 8-line decoder chip, SN74HC138.
It has three enable lines - G1 (active high) and G2A and G2B (both active low). Since I want the chip to be permanently enabled, I want to tie G1 to 5V and G2A/G2B to GND. But do I need to use pull-up / pull-down resistors, or can I tie the pins directly to Vcc or GND?
I think you can just tie them. Pull resistors are only used so that the line has a passive default state that can still be changed.
If the inputs aren't high impedence (ie. a bunch of current will flow through them if you just tie them), then you need a resistor to limit the current. You probably don't.