can anyone please give the circuit of the oscillator inside the 8051.all the books i've seen give the pin connections to the crystal,but not the oscillator.
Don't know which books you are referring too. The hardware chapter of original Intel MCS51 users manual has not less than three pages describing the internal oscillator circuits of the different 8051 (HMOS, CMOS) variants. https://www.edaboard.com/threads/206242/