What is the design for the reset circuitry for 8051?

Question

I would like to know as to why we choose the conventional R=10k and C=10uF in the reset circuitry

Answer 1

it just adds some delay from the time the power is turned on to the time the reset line goes high. the 10k resistor causes the cap to slowly charge. you could use other values of R and C, but you need a minimum low time for the reset to work.