Transistor logic is always going to have an inverter. You would need to add an extra inverter to get an AND or OR gate, so you might as well make the NAND and NOR the primary gates and derive the AND and OR from them + an inverter.
You can build a NAND gate and NOR gate using minimal amount of transistors. And you can make other gates using minimal ammount of universal gates.
So in most cases Digital Gates are made by combining NAND and NOR gate.
i m very confuse about what is the different btw ttl and cmos technology how the r differ in there fabrication plz describe me in deep or give any link that give complete knowledge ..........................thnx!!!!!!!