Most demos were written in 68000 assembly language, although a few were written in C and other languages. To utilize full hardware performance, Amiga demos were optimized and written entirely for one purpose in assembly (avoiding generic and portable code). Additional performance was achieved by utilizing several co-processors in parallel with the 68000. These co-processors include, Copper (a co-processor for synchronizing custom chipset writes to video display sync) and Blitter (a chip capable of quickly moving blocks of graphical data from one position on the screen to another). To achieve the best speed most demos disabled the operating system and addressed the hardware directly.