Widespread Myths

[[!redirects Widespread Myths on wheels]] These are myths that frequently show up that mislead people into writing bad code based on false perception of what the system actually does.

Myth: The PPU steals cycles from the CPU if there are a lot of sprites on-screen.

Fact: The PPU does not stea ...

Making a Small Game - Tic-Tac-Toe

When you have finished this tutorial, you will have written a small game. Things you have to know before you start:

  • 65816 assembly
  • Interrupts (What are NMI and VBlank)
  • What is VRAM, CGRAM, and their basic structures
  • What is DMA and how to use it
  • Video modes (mode 0), using backgroun ...

Backgrounds

BG Modes

The SNES has 7 background modes, two of which have major variations. The modes are selected by bits 0-2 of register $2105. The variation of Mode 1 is selected by bit 3 of $2105, and the variation of Mode 7 is selected by bit 6 of $2133.

Mode    # Colors for BG
         ...

Rendering the Screen

Mosaic

The mosaic filter is applied after the BG is rendered and scrolled but before it is clipped, combined with other BGs, pseudo-hiresed, or mathed. Each XxX block of pixels is replaced with the upper-leftmost pixel of the block. The 'blocks' are such that the upper-leftmost block is at th ...

Registers

Address Bus B Registers

TODO: note on fast access time

Register Address Name Style Access Timing
Screen Display ...

Translucency

Translucency is a cool effect, an example would be the water effects in Secret of Mana. I'm just not in the mood to chat, so let's get right into it.

We normally set things to the Main Screen register ($212C) in order to see them on the screen. ...

Mode 7 - Scaling

Mode 7 is a BG mode that allows a background to be rotated, scaled, and skewed. There are more possibilities when HDMA gets involved, Mario Kart. Let's get started with the basics.

Prerequisites

You need to understand fixed point comple ...

Working with VRAM - Initializing Tiles and Tile Maps

Now in this part of the series, we'll actually be.. Working with VRAM. :)

What We're Covering

Now we're going to actually upload data to the Video RAM. Now, there's 2 things that need to go to VRAM, and that's the tile data itself, and the tile map, which says where specific tiles will be di ...

Mega Man X3

Mega Man X3

Decompression Routine

People always assume "OMG MMX3! this game uses a [[C4]] chip, the [[C4]] chip does the decompression blah blah blah" well I proved them WRONG! [[C4]] chip is ONLY responsibl ...