8-bit CPU Zilog Z80 operating at 10Mhz. 8KB of ROM for bootloader. 56KB of RAM.
IO:
Reading data from FAT16/FAT32 SD Card. Reading/writing to RS232 port. 2 MegaDrive/Genesis-compatible controllers. PS2 Keyboard.
Video:
224x192 pixel resolution. 25 fps (half PAL fps). 256 Colors (RGB332). 2x2 virtual background space (448x384 pixels), with bi-directional per-pixel scrolling, described using 4 name tables. 64 sprites with width and height 8 or 16 pixels with possibility of being flipped in X or Y axis. Background and sprites composed of 8x8 pixels characters. Character RAM with 1024 background characters and 1024 sprite characters. 64 independent background horizontal scrolling in custom lines. 8 independent background vertical scrolling in custom lines. Overlay plane with 224x48 pixels with or without colorkey transparency. Background attribute table. RGB and Composite PAL output through SCART socket.
Sound:
PWM generated 8-bit 4 channel sound, with pre-defined waveforms (square, sine, sawtooth, noise, etc.). 8-bit 8Khz PCM samples in one of PWM channels. YM3438 FM synthesis chip updated with instructions at 50Hz.
@xj9 This is particularly interesting for two reasons: 1. he's generating a raw PAL signal from a microcontroller 2. It's tile-based, like all classic consoles, and unlike every other "retro homebrew" setup.