Assembly - the effect on EAX by AL -

i'm aware following code:

mov al, 8 ;  

will put value 8 (decimal) lowest byte of eax. however, if eax has decimal value 1 stored therein, happens, overwrite it?

so...

xor eax, eax ; inc eax ;  mov al, 8 ;  

does eax contain decimal 8?

yes copies , replaces destination operand source operand, source operand unchanged.