Found an interesting link - Accolade Vs Sega 1992 Law Case

[Munkyears]

http://digital-law-online.info/cases/24PQ2D1561.htm

Pretty good reading if your into Sega's history.

Joe

[Shiru]

I've thought it is well-known, isn't?

[Chilly Willy]

To most people in the computer/console world, yes, VERY well known.

[notaz]

I found this part interesting:

After expedited discovery and a hearing, the district court granted Sega’s motion. Prior to the hearing, Sega introduced the declaration of Takeshi Nagashima, an employee of Sega. Nagashima stated that it was possible either to create a game program which did not contain the TMSS code but would still operate on the Genesis III, or to modify a game program so that the Sega Message would not appear when the game cartridge was inserted. Nagashima stated that he had been able to make both modifications using standard components, at a total extra cost of approximately fifty cents. At the hearing, counsel for Sega produced two game cartridges which, he represented, contained the modifications made by Nagashima, and demonstrated to the district judge that the Sega Message <977 F.2d 1517> did not appear when the cartridges were inserted into a Genesis III console. Sega offered to make the cartridges available for inspection by Accolade’s counsel, but declined to let Accolade’s software engineers examine the cartridges or to reveal the manner in which the cartridges had been modified. The district court concluded that the TMSS code was not functional and that Accolade could not assert a functionality defense to Sega’s claim of trademark infringement.

Strange they call it "Genesis III", I suppose they meant VA3 of MD1? Genesis 3 was not released until much later.

Also what's up with TMSS bypass cartridge, you can't really bypass it unless you set it to jap region, right?

[Jorge Nuno]

Um... not the VA3, the first TMSS machine is the VA5 rev.

"...modifications using standard components, at a total extra cost of approximately fifty cents." This could mean a regular 74HC chip, and indeed you can use an OR-gate (74HC32) connected to A23 and A22 and use the output as a rom chip select. The /Cart pin must be pulled high, too.

[Chilly Willy]

Yes, the bypass cart is the interesting part from an engineer's pov.

If I had to guess, I'd say what the cart does is simply assert /DTACK on every cycle for any address. We know that the Genesis doesn't assert /DTACK for certain address spaces, and that accessing said spaces will hang the Genesis. It's possible that the TMSS simply turns off /DTACK for all spaces. Supplying your own /DTACK would defeat such a thing. It would also fit the description from the court docs.

[HardWareMan]

"...modifications using standard components, at a total extra cost of approximately fifty cents." This could mean a regular 74HC chip, and indeed you can use an OR-gate (74HC32) connected to A23 and A22 and use the output as a rom chip select. The /Cart pin must be pulled high, too.

I'd used two diodes and one resistor. More cheaper. :3

[TmEE co.(TM)]

you can only use differently routed trace too

!CARTIN high and A23 to !CE and you got a TMSS bypass DMA will fail if the ROM on the cart is too slow but otherwise it will work fine :3

[eteream]

Nagashima stated that it was possible either to create a game program which did not contain the TMSS code but would still operate on the Genesis III...

That's easier:

Code: Select all

char strng[]={'S','E'-'S','G'-'E'-'S','A'-'G'-'E'-'S'};

aux = 0;

for(i=0;i<4;i++) {aux+=strng[i]; tmss[i]=aux;}

I don't know if this is enough to don-t violate trademarks because it shows the tmss screen. But you don't write SEGA in your ROM. What a protection!!!

More, this paper tells (something like) that TMSS code is a header (or a mark) in the ROM, but as far as I know that is not true.