TMS9918Acompatible

TMS9918Acompatible is a designation used for hardware or software that adheres to the behavior of the TI TMS9918A Video Display Processor (VDP). Components labeled as such are designed to reproduce the original device's register interface, memory layout, and timing so software written for the TI VDP can run with little or no modification.

The TMS9918A VDP supports 256 by 192 pixel graphics and text with a 16-color palette. It uses 8 by 8 pixel tiles, a 32 by 32 tile map, and dedicated VRAM for pattern data and name tables. The VDP provides sprite support with up to four sprites per scanline, sprite attributes, and basic collision and interrupt features. It also supports horizontal and vertical scrolling and color emphasis.

For a device to be considered TMS9918A-compatible, it must expose a compatible register set and memory map and reproduce the same timing characteristics that software expects from TI's VDP. Some implementations may add enhancements—such as additional color modes or higher resolutions—that can be used in a compatibility mode, but true compatibility emphasizes faithful emulation of the original VDP on software that relies on it.

Examples of TMS9918A-compatible implementations appear in retro computer and console projects, FPGA cores, and software emulators. The label signals portability of games and tools across systems that originally used the TI VDP, facilitating cross-platform development and preservation of legacy software.