I tried to compile a 'Hello World' program from http://www.keil.com/download/docs/305.asp using Keil. I get the following error assembling startup400.a51... startup400.a51(185): error A84: OPERATOR REQUIRES A CODE/ECODE ADDRESS Target not created Line 185 corresponds to the below instruction ljmp far sanity_check ; Sanity check: Make sure 24 bit mode is on However if i remove the directive far then the code compiles. I'm using C Compiler: C51.Exe V8.01 Assembler: AX51.Exe V3.01 Linker/Locator: LX51.Exe V4.03 I havent changed any options and verified that extended assembler and linker options have been ticked.. Any ideas on how to resolve this?? I'm kinda new to keil.