Hi.. i know it would sounds silly but i guess i need someone to clarify this with me again.

Does power supply source, 5v, 9v, 12v or whatever voltages directly connected to the input of a logic gate always mean a logic of 1?

What if i tied my Vcc source to a switch, then connected to a logic gate input like 7404 inverter. Will the output always be a logic 0?

Vcc ----o___o---- i/p ==> o/p of '0'?
Vcc ----o o---- i/p ==> o/p of '1'?

On side note, i mean does Gnd always implies a logic of 0 while Vcc a logic of 1?

 

Does power supply source, 5v, 9v, 12v or whatever voltages directly connected to the input of a logic gate always mean a logic of 1?

Usually. It depends on the \(V_O_H\) (Voltage output high) and \(V_O_L\) (Voltage output low) of

your logic gate. For example, if I set \(V_O_L = 1V to 2V\) and \(V_O_H = 4V to 5V\), then the only point at which I get a logic "1" is when my voltage input is greater than 4V and less than 5V.

What if i tied my Vcc source to a switch, then connected to a logic gate input like 7404 inverter. Will the output always be a logic 0?

Again, the post above still applies here. If your Vcc was at 4.5V, then yes, it would invert appropriately.

On side note, i mean does Gnd always implies a logic of 0 while Vcc a logic of 1?

You can think of Vcc as simply the voltage required to power your logic gate. Ground is always 0V, and may not be necessarily a "0" to a logic gate.

I would suggest that you take a look at some of the logic gate datasheets to get an idea of how this works.