Using CPU register C as a counter, create an assembly language program, which takes each byte in turn from a source plain text memory block P, range 0x2000 ... 0x2009, XORs each byte with a symmetric encryption key K of value 0xC8, then stores consecutively each cipher result in a cipher result memory block X: range 0x4000 ... 0x4009.

This encryption process can be described as Xi = (Pi K) (where i is an index across the source and result memory blocks). Note is the symbol for XOR.

Add comments to your code clearly indicating what you have done.