Reset MCU with a 1-0 button
You usually pull the reset pin for 2 machine cycles to reset the 8051 Microcontroller. You could do that easily using a push button, as per the following circuit.







simulate this circuit &ndash; Schematic created using CircuitLab

This would straight away, work. 

But if you wish to have a better more universal reset button, you could follow the following schematic.







simulate this circuit

Both will do the job.