The commands (instructions) are native instructions to the 68HC11 and therefore it is termed a low level language program. Examining the program the instructions (mnemonics) they are difficult to understand e.g. ldaa #$40. In order to make life easier we program in High level languages which resemble 'English' statement e.g. Input, print, Sin(x) etc. Let us return back to our block diagram of a computer system. Where does the program reside? Attached to the process is a fourth block termed Memory (storage). The program resides in memory, so the CPU reads and executes the program from the memory block. It is also possible to use the memory blocks as input/output e.g. The draughtsman could enter his drawing to screen and store it in memory.