Testing:
- More tests for branching operations
- More tests for CMP/CPY/CPX operations
- Tests needed for JMP operations
- Tests needed for LD* and ST* operations
- Tests needed for IN* and DE* operations
- Tests needed for T** transfer operations
- Tests needed for interrupt support
- Tests needed for the numerous other operations added
CPU:
- Implement complex addressing modes for many operations
- More work on interrupts
- Decimal mode support
- Better emulation mode support
- Have each operation return the number of cycles used by the execute function.
- Implement the rest of the missing operations.
- Optimization
Memory:
- Bank wrapping or not wrapping for certain addressing modes and with certain
  settings
- Page wrapping or not wrapping for certain addressing modes and with certain
  settings
- ROM protection
- Memory mapped I/O
Display:
- Using the html page included provide a nice interface for using the cpu 
  emulator and provide many features helpful for debugging
- Assembler and disassembler