Hi Vlad,

you best look at:

http://www.atmel.com/atmel/products/prod72.htm

There you'll find a document called:

AT89S8252 Primer

which describes the operations which you attempted.

However, one thing I wouldn't do:

XRL a bit is elegant, but since it only toggles the bit, you never know whether it has the desired state. Better ORL to set it and ANL with the inverted mask to reset the bit.

Hope this helps

Jürgen