The code segment is actually taken from TinyBASIC Plus and I am trying to extend the program memory by using an external SRAM IC. From having a look at the code, the char array called program seems to be where the BASIC program (written in TinyBASIC Plus) is stored so I am planning on replacing all calls to this variable with calls to the external SRAM IC. I am stuck at the point where another variable (program_start) is equal to the program array (as shown in the first post) as I am not sure how to make an array stored in the SRAM IC equal a variable stored in the AVRs internal SRAM without copying the contents of the SRAM IC to a variable in the AVRs internal SRAM (I cannot do this as the array stored in the SRAM IC could be larger than the internal SRAM).