Gopal

You wrote:

"R/W is connected to output of a latch formed with RD and WR signals."

1) Would you please explain above?
2) Is there some other memory mapped H/W in your project or LCD alone?
3) If nothing else than LCD, why you are using it in a memory mapped manner. I prefer to drive LCD directly from a single port in 4-bit fashion. It only takes 7 I/O pins.

Also you must use pull up resistors with PORT0.

Regards

IA