connect AddressingMode with instructionBytes
refactor AddressingMode
refactor AddressingMode
refactor Opcode
fix comments
refactor CPU
format CPU
format
correct the use of zero flag
simplify code
refactor CPU
refactor Instruction. BROKEN!!!
fix Instruction, STILL BROKEN
insert blank lines
refactor Instruction, make all concrete instructions inner class
refactor Instruction, use public static inner class
fix compile errors!
refactor
refactor
refactor, rename Opcode to InstructionSet