i agree...but what about this. this should work but it does not.

; turns on LED when button is pressed & retains its state
;AT89C51, P1.0 is LED,P1.1 is connected to push sw.

ORG 0

MOV C,P1.1 ;get the button state
MOV P1.0,C ;display button state on LED

Loop: ; loops forever & led's state in prev. step is retained
SJMP Loop

END