A few years ago someone in Canada showed up with evidence of a prototype of the rumored Sega Graphic Board, developed by Sega Japan, that was mentioned in early magazine publications circa 1987. The hardware that appeared apparently passed hand to hands in a typical impossible-to-verify cross-country flea market story. Eventually the owner decided to sell it and the tablet was recently auctioned on eBay. I am happy to announce that I got hold of the hardware and software :)
Sega Graphic Board v2.0 Prototype for Master System, now available! The hardware prototype appears to be dated May 1987, the software prototype Ausugt 1987, that is, 27 years old. The tablet plug into regular controller port, has 3 buttons and an input resolution of about the Master System 256x192 resolution. According to a signature left in the ROM data, the software was created by Kazuo Wakihara also responsible for handful of early Sega classics including later hit Columns.
The Sega Graphic Board may have been apparently planned to be supporting hardware for the Megadrive, as pictured in early prototype pamphlet showcasing the Megadrive along with an unreleased floppy disk drive and the graphic board:
The software attempts to reproduce a fully editable 16 colors bitmap using the Master System character-based video mode. The drawing area is restricted to 176x144 pixels which is close to the maximum unique drawing surface given the Kilobytes of video memory. The software offers variety of drawing tools, including useful "copy" and "magnify" tool. Unfortunately no "line" or "undo".
More pictures of the hardware,
Picture from the original owner (the board is upside down!)
As of today the hardware is emulated by Meka Wip 2014-10-04 and will be shortly be supported by MESS and Emulicious among other emulators. The reverse engineering thread provides enough information if you want to implement support for the Sega Graphic Board in your emulator.
Thanks to kusfo, hang-on, Maraakate and SF for their donation toward acquiring the lot! Thanks to Maxim and jdg for help reverse engineering the hardware. Enjoy!