digital logic gates.

[Bhuvanesh Nick]

i seen in it in a page it is mentioned we are using positive logic systems that is above +2v for on and below 0.8 to for off.but in below statement its said to ground for 0 .if i do so it looks like - voltage ..help me plzz

"we can define the ideal Digital Logic Gate as one that has a "LOW" level logic "0" of 0 volts (ground) and a "HIGH" level logic "1" of +5 volts and this can be demonstrated as:"

 

[electroM]

The statement above is in regard the IDEAL GATE but in physical world we don't have Ideal behaviors hence we use approximation.

also the logic levels for different IC family like TTL, ECL, CMOS etc. are different. hence first understand logic three levels.