Hi, I'm trying to run KEIL UV2 on custom desing Monitor board that consist of AT89C51 CPU, 32KByte von Neumann ram decoded at 0x8000H. MON51 is installed at internal Flash address 0x0000H.The problem is that I can't port the C programs. If i assembled an assembly programms that Start at 8000H, and download it to monitor than it run very smoothly. But if made programms in C and compile , Link/Locate with all the options mention in the manuals then sometime it run and sometimes it craches.I've set the starting address of off Chip Code to 0x8000, off Chip XDATA Memory to 0xA000, modify STARTUP.A51 etc... Now i wannt to know that wheather i have to select "USE ON CHIP ROM" option or not. Can anyone help me out Do I need to modify my hardware to run C programms. How to make C programms that start from 0x8000H absolute.. Thanks Wahab