ok now
9600,N,8,1 works well with MCU for 0-255 but PC was not determinig the two 0s value.
hyper terminal is still showing the black rightward sign for 2 consecative zeros but VB does not show anyone therefore VB is right (null showing) but buffer count increases which is clear that some is receiving.
i was checking hyperterminal. 0 is null char. but 2 zeros are making sign given in picture below (rightward black sign).
that was confusing me to go on parity communication. but it might be the only one case to show 2 null char by that sign which come only for consec. zeros not any other time like for 0 and 1, or 0 and non zero value.
also PaulHolland , parity check communication is supported on at89c51 using TB8 and RB8 bits in 9 bits UART mode. i just missed to check the Parity flag, if i change that then that communication will also be good as other on MCU at89c51.