This is just sharing the Sega Mega Drive TMSS Disable project from https://github.com/consolesunleashed/sega-mega-drive-tmss-disable. All credit goes to Consoles Unleashed for the PCB designs and to Wurthless-Elektroniks for the ATtiny85 code.

The mod removes the TMSS “Produced by or under license from Sega” boot screen on Mega Drive / Genesis consoles from Model 1 VA6 onwards. The ATtiny version briefly resets the 68000 through /VRES at exactly the moment the cartridge is enabled, so the console boots straight into the game with no trace cuts.

There are five boards: ATtiny Basic, ATtiny Quick Solder Board (QSB) Short and Long, and a Logic version built around a 74HC4066 (Basic and QSB), based on a schematic by Trimesh. The QSB versions use half-cut castellated holes that sit directly on the cartridge-slot pins, while the Basic boards are wired in. All parts are SMD on one side, the author recommends 0.8–1.0 mm PCB thickness for the QSBs, and the ATtiny must be programmed with the correct fuses before soldering.

Please keep a link back to the original repository and credit the author, as the project’s licence requests.

WARINING

Logic QSB v1.0 needs a TSSOP‑14 chip, not SOIC‑14. The upstream BOM lists 74HC4066D,653, but the pads are 0.65 mm pitch, so that chip won’t fit. I changed it to 74HC4066PW,118.

Logic QSB’s resistor is 0603, not 0805.

QSB Long has a /MRES solder jumper (JP1) that is open in copper, but the paste layer covers both pads. Reflow will probably bridge it, so tell PCBWay whether you want it open or bridged.

The ATtiny boards have no programming header. The chip must be programmed before assembly with fuses L 0xF1, H 0xDF, E 0xFF.