Hi all,
I m new here and in programing uP too. We had Atmel in school and... and I love it. I bought programmer ISP for fun and trying "develop" someting.

I know a little instructions of ASM from school. But:

I have uP AT89S51 at home and trying use LEDs (Output I/O) as first step. But I can not guess/find/think... where are address of I/O pins. I looked on datasheet and they
say someting about :080H,090H addres - but compilator says someting about "out of memory" when i Try:
.EQU portX = 80 ...¨

In AVR studio is a example with "out" instruction,
The example is:
ldi r20,someting
out $18,r20
But it works very very wired, example when i try set
00O01000 to $18 - 2 diods glowing, 6 not. I tried a lot of addres - "$8-$20" but everything is wierd. And glowing diods only on port P2.X.

AVR studio do NOT suppért AT89S51, I downloaded older version (3.56) and select "Custom"

My question si :
How i can set 0 and 1 to all I/O ports on AT89S51 - output?

(I read article where say: "You must select if is PIN output or input" - where? ), where is a adress of this special register for port A,B,C,D(1,2,3,4)

Or is a trouble with AvrStudio when AT89xxx are not support and compiler stoping me on lines like:
(P0 data 0x80) or (.EQU portA =80)


Very thx and have a nice day (here in czech rep, good deep nite)