genesis-core

Sega Genesis / Mega Drive emulation core.

The Genesis contains the following components, some of which were reused from the Master System:

68000 CPU clocked at 7.67 MHz
Z80 CPU clocked at 3.58 MHz, meant primarily for audio processing
VDP (video display processor) that is based on the Master System VDP but adds yet another more advanced graphics mode
- Can render in either 256x224 or 320x224; PAL consoles additionally support 256x240 and 320x240
- Supports 9-bit RGB color with up to 64 colors onscreen simultaneously
- Supports shadowing and highlighting to create additional colors beyond the 512 colors of 9-bit RGB
- Supports two background layers with per-pixel priority
- Supports per-scanline and per-16px-column background scrolling
- Supports up to 80 sprites per frame and up to 20 sprites per scanline, with sprites ranging in size from 8x8 to 32x32
YM2612, an FM synthesis sound chip
- Contains 6 fully configurable FM synthesis channels, each with 4 operators that can be arranged in 1 of 8 different configurations
- One of the 6 channels can be swapped out for a raw DAC channel which directly outputs a PCM sample
- Output frequency of 53.267 KHz
SN76489, a PSG lifted directly from the Master System
64KB of working RAM for the 68000
8KB of working/audio RAM for the Z80
64KB of VRAM
128 bytes of CRAM (color RAM for storing palettes)
80 bytes of VSRAM (vertical scroll RAM for storing per-column V-scroll values)

This crate contains code for the following: