cardiograph-computer/notes/todo.md

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/

Documentation

• Improve docs for flags register
• Play with JSDoc

Design

• Add keypad to memory map (see dev note)
• Replace CHP/CFC with FHP/FTG
• Add a flag for bank-switching to the ~zero-page

For consideration

• Subroutine stack
• Extended system (secret bonus operations)

Programming

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

Run-scripts

• Change interface to run in non-debug mode by default, and use a flag to select debug mode:
  • ./run-cpu.js foo.asm
  • ./run-cpu.js --debug foo.asm
  • ./run-cpu.js -d foo.asm

Simulator

Assembler

• Pad up to 256 bytes
• Validate labels
• Return pure machine code when printing to stdout (and not in debug mode)

CPU

• Add single-stepping

Possible under-the-hood improvements

• Do a proper binary version... (or lose the typed arrays?)
• Extract debugging to its own module
• DRY out addition and subtraction