Gameboy Display Information

This post is a work in progress.



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Uses register WX and WY to set starting position of the window display.

Scroll Registers

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Scrolls the background screen horizontally and vertically.

LCD Display RAM

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Character RAM

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Background Map Data

Window Overlay

Bringing it together

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How to read tile patterns for background tile map

  1. Determine which memory range is being used for background map
    • Either $9800 - $98FF or $9C00 - $9FFF.
    • Selected using Bit 3 of LCDC control register
  2. Determine Character Data range
    • Either $8000 - $8FFF (Range 1) or $8800 - $97FF (Range 2)
    • Bit 4 of LCDC control register.
  3. Iterate through bytes in background tile map range that was determined (1)
    • If Range 1 of Character Data is selected
    • interpret byte from background map data as unsigned (0 - 255) and read tiles starting at $8000 * If Range 2 of Character Data is selected
    • interpret byte as signed (-128 - 127) and read tiles staring at $9000

Character Composition

Object Attribute Memory

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DMA Transfer

Example routine for using DMA

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