H bridge motor circuit

Hi,
Wish to know the components and their values for this circuit?
Please help !

And if i need to rotate the motor forward/reverse using PIC 16f877 what should i do ?

What are B and C in this circuit?

Just A is enough to rotate in both directions?

THANKS

It is a bridge. If you don't properly drive all 4 inputs then it will make a lot of smoke.

For the motor to turn one way, A and B must be low, and C and D must be high.
For the motor to turn the other way then A and B must be high and C and D must be low.

why don't you google for "h bridge circuit mosfet" You will be surprised how many hits you get.

and, yes, just having 4 "naked" control lines is risky. Turn on both the upper and lower mosfets and you've created a short to ground. poof!