You must not let any input float.
If you use only two Ax inputs, then you can get only four outputs. If A2 is low, you get the first four outputs; if A2 is high, you get the last four outputs.
(Why did you choose a military-grade bipolar device? The SN74LV138AT…
Part Number: SN74ACT04 Other Parts Discussed in Thread: CD74ACT138 , SN74LV138AT , SN74CBT3251 , SN74AHC541 , TCA6408A Hi,
Want to know output state at power up for ACT logic. For example if ACT04 input A is tied to GND (low), what will be situation on output…