TMS9918 VDP display modes

The basic TMS9918 features 3 display modes:

• Text Mode: 240×192 pixels total, as 40×24 tiles, pulled from 1 tile set of 256 6×8 pixel characters. The entire tile set has a 2-color limitation. This mode doesn't support sprites.
• Graphic Mode 1: 256×192 pixels total, as 32×24 tiles, pulled from 1 tile set of 256 8×8 pixel characters. Each group of 8 tiles in the tile set has a 2-color limitation. For example, the tiles "0" through "7" will all have the same color attributes.
• Multicolor Mode: 256×192 pixels total, 64×48 changeable virtual pixels, as 32×24 semi-graphics characters. These semi-graphics are defined in a special character set of 256 characters defined by 2×2 "fat-pixels". There are 4×4 pixels in each fat-pixel, but the pixels within a fat-pixel cannot be individually defined, although each fat-pixel can have its own color, hence the name of this mode (Multicolor). This mode is very blocky, and rarely used.

When designing any software, consider only these modes, as they exist in all variants and successors of the Texas Instruments TMS9918 Video Display Processor. This is intended for compatibility with all TMS9918 compatible Video Display Processors.