An interesting observation. It prompts the thought of how far away this simulator is from an actual ZX81, and how much it has been pulled away from a ZX81 by dint of training data where simulated retrocomputers of other types all boot into copyright messages. I wonder how often the spicy autocomplete engine tried to make it put up a "READY" or "OK" prompt.

One ZX81 clone actually did have a "READY" prompt, I read. Actual intelligence was doing the same in the 1980s. (-:

The ZX81 did not have a copyright on boot.

Can you say what parts Claude was used for to speed this up?

My guess is most of it? This commit message for example sounds very much like a Claude result:

    Add Space Invaders game implementation in assembly language
    - Implemented the core game logic including player movement, missile firing, and invader behavior.
    - Added collision detection for missiles and bombs.
    - Included game state management for win/lose conditions and restarting the game.
    - Created functions for drawing game elements on the screen and handling keyboard input.
    - Defined constants and variables for game configuration and state tracking.

That last one in particular is exactly the kind of update you get from claude, it doesn't sound very human. "Constants and variables" eh? Not just constants or variables, but constants and variables.

Helpful, but not. Detailed, but not.

Fast / slow mode breaks “Space Invader” by the way.

Looks nice, however on laptop screens not all buttons are visible, it took a while to discover I could scroll to find "Assemble and Run".