Dear sir, I am using C8051F124 microcontroller.i am connected 64KB external memory to the upper ports (as multiplexed mode) and i am writing program by using Keil compiler to display the externally stored data (from 0x0000 to 0x2000) on the LCD. In the Target dilog box of keil compiler i am selected memory model as small:variables in DATA then the program was working fine. When i am selecting memory model as Large:variables in XDATA then the program was not working and LCD was not initialising. Please tell me the solution. Thanking you.