To do

Research

Learn how the C64's PC gets initialized (what is the initial value? how is it set?)
Review CHIP-8
- read about the spec / ISA
- read these, and add them to the bibliography:
  - Steve Losh: https://stevelosh.com/blog/2016/12/chip8-input/
  - https://tonisagrista.com/blog/2021/chip8-spec/

Add a flag for bank-switching to the ~zero-page
Move the initial IP value, to eliminate the gap between it and the keypad pointer
- see paper notes
Consider adding a VIP-style keypad-based machine code monitor
reconsider ISA order in light of supercat comment here
- Why didn't the 6503 have increment/decrement opcodes for A?
Re-order flags to put Overflow at the end (since it would be nice to be able to easily ignore it when introducing someone to the basics of the CPU)

Write some more complex test programs
- Display (hex) numbers
- Greater than
- Minimal LOGO-ish interpreter for turtle graphics

Return pure machine code when printing to stdout (and not in debug mode)
Pass asm line thru to cpu to print when debugging
- asm: create a second array that stores every line with code (nor blank or comment only lines) + its line number
- cpu: accept an optional debugging array, print line # and statement
Validate labels

Allow running pre-compiled machine code

I'm thinking of an interface like this...

  $ ./cpu.js -mc code.bin  
  $ ./cpu.js code.asm
  $ ./cpu.js --debug code.asm

Full list of flags I want:

  -d --debug
  -s --singlestep
  -p --prettydisplay
  -mc --machinecode