sir, i am using your keil LPC 51 C-COMPILER as i request you send a one file startlpc.a51. But i facing one error in it Error L121 : IMPROPER FIXUP MODULE : Startlpc.obj Segment : ABSOLUTE OFFSET : 0000 i think its giving a error at cseg at 0 in startlpc.a51 i haven't initialized anything in my main program to start from particular location. if it will be initaialized 0 location some interrupts will occur upto 75h so that memory locations will overlap so please give me the details how c-compiler will initailize rom locations. and i am awaiting for your solution. thanking you Rgds/prafulla chandra k