i'm using an at89c52. i have some data, i've declared it:

unsigned long   total_entradas, total_salidas;

when i reset the mcu or power on it. the data in those vars goes 0. i want to store the data in those vars even if i cut the power.

is there a form to do that?
how can i do that?
where can i find examples?

Thanks,

Ruben Porras