4.7.1.3.2 XC8 Linker - Memory model options Size of double This selector controls the size of the double type. See 4.6.14.1 Short Double Option. Size of floats This selector controls the size of the float type. See 4.6.14.2 Short Float Option. External memory This selector controls how external memory is accessed. See 4.6.1.9 Emi Option. RAM ranges This field adjusts the data memory used by the program. See 4.6.1.17 Ram Option. ROM ranges This field adjusts the program memory used by the program. See 4.6.1.20 Rom Option.