Everything about MAD-65 is written down. These are the working documents the machine was designed from — not a marketing summary of them.
The one to start with. A practical, example-driven manual for writing MAD-65 games in 6502 assembly with the cc65 toolchain: the frame model, the OS kernel API, reading joysticks, drawing sprites and text, music and sound effects, the 3-D vector library, cartridge loading, and using the simulator.
The firmware on the game CPU: the API jump table, command builders, audio and joystick helpers, fixed-point maths, the cartridge interface and the frame loop.
The firmware on the graphics CPU: the drawing instruction set, sprite, tile and font formats, the blitters, and diagnostic mode.
Designed but not built: “comb” rendering for ghost sprites and layered backgrounds, and vertical (TATE) mode for portrait games. Recorded so the design work does not have to be redone.
The whole machine in one document: both memory maps, the ping-pong shared RAM protocol, the boot sequence, clocking, and the component list.
How the picture is made: horizontal and vertical counters, sync timing, the double-buffer swap, the free background copy, CPLD pinouts and the resistor network on the VGA output.
Every decode equation for both CPUs, the wait-state generator, the shadow RAM switch, and the diagnostic LED registers.
Per-board list of integrated circuits for PCB1, PCB2 and PCB3.
They are long, and they are written for someone who intends to build or program the machine rather than to browse it. Each one opens with a table of contents; if you are here out of curiosity rather than intent, the hardware page covers the same ground in a tenth of the words.