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Atari RBI Baseball (VS) freezes in attract mode [SOLVED]
http://forums.nesdev.com/viewtopic.php?f=3&t=14400
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Author:  zeroone [ Tue Jun 14, 2016 7:46 am ]
Post subject:  Atari RBI Baseball (VS) freezes in attract mode [SOLVED]

The attract mode (the demo) of Atari RBI Baseball (VS) freezes in Nintendulator, puNES and my emulator just prior to the moment that the first batter swings at the ball. Below is a screenshot from Nintendulator illustrating when all 3 emulators freeze (it's using the incorrect palette, but it's an MMC3 game, which should run perfectly).

Image

It's stuck here:

Code:
09:A1DF:4C DF A1  JMP $A1DF


It looks like it is waiting for an interrupt that never happens.

The game runs correctly in Nestopia, FCEUX and RockNES.

If anyone has an insight into this, please let me know. Thanks.

Edit: I noticed that Nestopia lists the game as Mapper 206 (NES-DRROM), not MMC3.

Author:  Sour [ Tue Jun 14, 2016 10:34 am ]
Post subject:  Re: Atari RBI Baseball (VS) freezes in attract mode

Mesen had the same freeze issue so I took a look.

This is a copy protection scheme - FCEUX & Nestopia both emulate it.
If you check FCEUX or Nestopia's source, they both implement 2 extra read-only registers ($5E00 & $5E01) and the game expects specific values from $5E01 after a number of consecutive reads.

This is mentioned very vaguely on the wiki in the NES 2.0 specs:
Quote:
M: Vs. mode:

0 - Normal- no special mode(s)
1 - RBI Baseball (protection hardware at port 5E0xh)
2 - TKO Boxing (other protection hardware at port 5E0xh)
3 - Super Xevious (protection hardware at port 5xxxh)


Implementing the same fix as FCEUX/Nestopia fixes the freeze on my end.

Author:  lidnariq [ Tue Jun 14, 2016 10:39 am ]
Post subject:  Re: Atari RBI Baseball (VS) freezes in attract mode

zeroone wrote:
Edit: I noticed that Nestopia lists the game as Mapper 206 (NES-DRROM), not MMC3.
The only Vs. System game that added hardware with an IRQ was Platoon, on the Sunsoft-3 IC.

Author:  zeroone [ Tue Jun 14, 2016 11:44 am ]
Post subject:  Re: Atari RBI Baseball (VS) freezes in attract mode [SOLVED]

Sour wrote:
This is a copy protection scheme - FCEUX & Nestopia both emulate it.
If you check FCEUX or Nestopia's source, they both implement 2 extra read-only registers ($5E00 & $5E01) and the game expects specific values from $5E01 after a number of consecutive reads.


That's it! Providing the security values with those registered solved this issue. Thanks.

lidnariq wrote:
The only Vs. System game that added hardware with an IRQ was Platoon, on the Sunsoft-3 IC.


I switched to mapper 206 per Nestopia's recommendation. It works under that mapper, but as mentioned above, the security values were required to solve the issue.

Thanks so much guys.

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