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.