Posted in 2025

The Versatile Playfield Kernel

In Atari 2600 programming, we struggle to draw two sprites and the playfield (background) within the 76-cycle budget of each scanline. For maximum-resolution single-line updates where we change parameters every scanline, we’d need to look up and write:

2 registers per sprite (color, bitmap) × 2 sprites = 4 registers

5 playfield registers (PF0, PF1, PF2, COLUPF, COLUBK)

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Tiny Atari 2600 ROMs

On the Atari 2600, a kernel is the term for the highly-optimized assembly code that draws the display, i.e. “races the beam”.

I was pondering a question: What’s the smallest Atari 2600 kernel you can write?

I found this AtariAge thread which packs entire ROMs into 32 bytes. Can we do better?

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