(c) 1985 Sega, Product number: GB-800


Description

The Terebi Oekaki ("TV Draw", also officially aliased as Sega Graphic Board), was released in 1985, in the early Sega Mark III days. It was available in stores for ¥8800.

The package consists in a cartridge linked to the board, and a plastic pen (although any object can be used instead). The board is made of gray plastic, with a transparent window where pen presses are detected. The cartridge plugs on the machine, and contains the drawing software and interface to the board. As a result, the board is not reusable for other software.

The drawing software is based on the SG-1000/SC-3000 video mode. Fifteen fixed colors are available to the user, but due to a video mode limitation, only two can be mixed in the same 8x8 pixel tile. This leads to bizarre modifications of the picture when user is trying to precisely plot points of different colors.

The drawing tools are very basic. The pen tool has three different sizes (1, 2 and 3 pixel wide) and there's of course an eraser. An interesting feature is the symmetric button, which when enabled, reproduce your actions, mirrored on the vertical axis. The background color is changeable (the 15 available colors cycles on user request), and it is finally possible to view the picture in fullscreen, with the tools bars removed. No saving feature is provided, unfortunately (it could have been done, using the Sega Recorder and tapes).

An interesting feature of the board (but also its main drawback) is the transparent window. The obvious usage is to stick the board on a picture, and be able to copy it on screen. Using the original hardware is unfortunately a frustrating experience. Considering the board as a child product released in 1985, one could guess that the technology used is a limiting factor. Using a plastic pen on a glass is unusual, and pen pressure is not always properly detected. Thus, tracing a full shape becomes a challenge and there's always fear of damaging the glass (pay attention, warranty must have passed already! ;-). It is possible to use the standard joypad to move cursor and simulate a pen pressure, but then, part of the experience is lost.

Back in 1985, it would be safe to say that beside its flaws, the Sega Graphic Board was an interesting product. The technology has improved since then, and similar software were released years later, such as Art Alive (Megadrive), Artist Tool (PC Engine) and its many peripherals, or the great Mario Paint (Super Famicom).

This is for sure a cool product to possess nowadays, being an obscure part in Sega history.

Software Pictures

Title screen Main screen Example picture Example picture

Available Goodies

Photos

Manual

(See also Higher-res scans added after this page was written.)

Picture Contest #1 Entries

Drawing Contest held from 2001-11-25 to 2001-12-01


Entry #1 by frsh

Entry #2 by Markish

Entry #3 by Death Adder

Entry #4 by Gutwein R.

Entry #5 by Smith-Perricone

Entry #6 by Maxim

Entry #7 by Bock


Download all seven entries: terebioekaki-contest.zip (42 kb) (includes savestates and GIF files)

Technical facts

The cartridge intercepts read and write to special locations, in order to let the software communicates with the board. The addresses are as following (although it is likely that the whole ranges are usable):

0x6000 (W) - Axis select.
    Bit 0: select axis

0x8000 (R) - Status register.
    Bit 0: pen pressure (reverse logic), Bit 7: currently computing data

0xA000 (R/W) - Data.
    Return selected axis, zero when pen is not on board.
    Write effects are unknown.

Information above were gathered by myself from reverse engineering, and may or not be incorrect. It is obviously difficult to study actual electronic mecanisms (since the board does not fill the axis data immediately), but the information are enough for emulating purpose. Any precision is welcome. Discussions goes on the S8-Dev Forum.


See the main page for Terebi Oekaki (テレビおえかき)



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