what are the IC's used for biasing opamps (both its negative terminal and positive terminal) i.e pin 4 and pin 7.

 

That is not a bias. A single op amp needs electrical power to operate. Pin 4 is the input for the negative voltage, and pin 7 (pin 8 if a dual) is for the positive voltage input. These voltages actually power the internal circuitry.

A bias is a voltage applied to one input pin - usually the non-inverting one - to give a permanent offset at the output.

Back to the voltage supplies - the IC's supplying regulated voltages would be, then voltage regulators. They are usually complimentary to one another, so if you use a 7812 to supply a positive 12 VDC to pin 7, you would use a 7912 to supply -12 VDC to pin 4. Google "voltage regulator ics" to learn more about them.

 

thanx ,,can you tell me what are the languages a microcontroller understands ?

 

Machine code specific for each microcontroller family, translated from different programming languages using compilers. If you really wanted, you could run Java on a PIC.