Bryan Chan wrote:
control equ 0FE03H ;
leds equ 0FE0???H; Implied but not stated.

mov dptr,#control ;load control word
mov a,#80h ;all outputs
movx @dptr,a

mov dptr, #leds ;address of leds
mov a,#00h; turn all leds off

movx @dptr,a

;works fine:all the leds stay off though !

Add an infinite loop which toggles them on and off and watch the result on a scope.

Steve