INES Mapper 185: Difference between revisions
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(→Bank select ($8000-$FFFF): Now that this isn't Disch's notes, let's edit for style.) |
(→Bank select ($8000-$FFFF): alternative workaround, plus a list of the specific tests done by each game (commented out)) |
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++---++- Used for CHR copy protection. | ++---++- Used for CHR copy protection. | ||
These games only have 8k of CHR, and they attempt to disable CHR by writing | These games only have 8k of CHR, and they attempt to disable CHR by writing a specific value to the CHR Reg, then VERIFY that garbage is read back, then they swap back to the actual CHR. If they don't get the expected garbage, they lock up. | ||
a specific value to the CHR Reg, then VERIFY that garbage is read back, then they swap back to the | |||
actual CHR. If they don't get the expected garbage, they lock up. | |||
Each game has their own value that enables/disables CHR. However, a simple heuristic obviates the need to detect each game individually: | Each game has their own value that enables/disables CHR. However, a simple heuristic obviates the need to detect each game individually: | ||
* if C AND $0F is nonzero, and if C does not equal $13: CHR is enabled | * if C AND $0F is nonzero, and if C does not equal $13: CHR is enabled | ||
* otherwise CHR is disabled | * otherwise CHR is disabled | ||
When CHR is disabled, the pattern tables are open bus. Theoretically, this should return the LSB of the address read, but real-world behavior varies. | |||
All of these games test for the bad value first, and the correct value (if at all) second; returning garbage for the first two reads from the PPU after reboot should also work. | |||
| Line 42: | Line 41: | ||
! !! colspan=2|if this value is written | ! !! colspan=2|if this value is written | ||
|- | |- | ||
! Game !! Must work !! Mustn't work <!-- | ! Game !! Must work !! Mustn't work <!-- specific test --> | ||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=1262 Bird Week] || 0x0F || 0xF0 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=1262 Bird Week] || 0x0F || 0xF0 <!-- PPU $1FF0 is NOT $0C with the wrong bank, then IS $0C with the right bank --> | ||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=1264 B-Wings] || 0x33 || 0x00 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=1264 B-Wings] || 0x33 || 0x00 <!-- PPU $0000 is NOT $3C with the wrong bank, then IS $3C with the right bank --> | ||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=1261 Mighty Bomb Jack] || 0x11 || 0x00 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=1261 Mighty Bomb Jack] || 0x11 || 0x00 <!-- J: PPU $0000 is NOT $00 with the wrong bank; E&U: PPU $0001 is not $3C --> | ||
|- | |- | ||
| Sansuu 1 Nen, [http://bootgod.dyndns.org:7777/profile.php?id=1263 Sansuu 2 Nen], and [http://bootgod.dyndns.org:7777/profile.php?id=4061 Othello] || 0x22 || 0x20 <!-- | | Sansuu 1 Nen, [http://bootgod.dyndns.org:7777/profile.php?id=1263 Sansuu 2 Nen], and [http://bootgod.dyndns.org:7777/profile.php?id=4061 Othello] || 0x22 || 0x20 <!-- | ||
S1N: PPU $000C is NOT $BC with wrong bank, then IS $BC in right bank ; | |||
S2N: PPU $0003 is NOT $42 with wrong bank, then IS $42 in right bank ; | |||
Othello: PPU $0006 is NOT $3F with wrong bank, then IS $3F in right bank--> | |||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=3791 Sansuu 3 Nen] || 0xFF || 0x00 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=3791 Sansuu 3 Nen] || 0xFF || 0x00 <!-- PPU $0006 is NOT $34 with the wrong bank, then IS $34 with the right bank --> | ||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=3592 Spy vs Spy] || 0x21 || 0x13 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=3592 Spy vs Spy] || 0x21 || 0x13 <!-- PPU $1F20 is NOT $55 with the wrong bank --> | ||
|- | |- | ||
| [http://bootgod.dyndns.org:7777/profile.php?id=2332 Seicross (v2)] || 0x20 || 0x21 <!-- | | [http://bootgod.dyndns.org:7777/profile.php?id=2332 Seicross (v2)] || 0x20 || 0x21 <!-- PPU $0700 are NOT $20,$60,$70,$70,$70,$40,$08,$38 with the wrong bank --> | ||
|} | |} | ||
Revision as of 04:17, 17 April 2016
iNES Mapper 185 is used for games that use the CNROM board with weak copy protection measures.
Example Games:
- Spy Vs. Spy (J)
- Mighty Bomb Jack (J)
Overview
- PRG ROM size: 16 KiB or 32 KiB
- PRG ROM bank size: Not bankswitched
- PRG RAM: None
- CHR capacity: 8 KiB ROM (copy protected)
- Nametable mirroring: Solder pads select vertical or horizontal mirroring
- Subject to bus conflicts: Yes
Banks
- PPU $0000-$1FFF: 8 KB switchable CHR ROM bank
Registers
Bank select ($8000-$FFFF)
7 bit 0 ---- ---- ..CC ..CC || || ++---++- Used for CHR copy protection.
These games only have 8k of CHR, and they attempt to disable CHR by writing a specific value to the CHR Reg, then VERIFY that garbage is read back, then they swap back to the actual CHR. If they don't get the expected garbage, they lock up.
Each game has their own value that enables/disables CHR. However, a simple heuristic obviates the need to detect each game individually:
- if C AND $0F is nonzero, and if C does not equal $13: CHR is enabled
- otherwise CHR is disabled
When CHR is disabled, the pattern tables are open bus. Theoretically, this should return the LSB of the address read, but real-world behavior varies.
All of these games test for the bad value first, and the correct value (if at all) second; returning garbage for the first two reads from the PPU after reboot should also work.
This table has been assembled from nocash and the sources of MESS, Nestopia, and FCEUX.
| if this value is written | ||
|---|---|---|
| Game | Must work | Mustn't work |
| Bird Week | 0x0F | 0xF0 |
| B-Wings | 0x33 | 0x00 |
| Mighty Bomb Jack | 0x11 | 0x00 |
| Sansuu 1 Nen, Sansuu 2 Nen, and Othello | 0x22 | 0x20 |
| Sansuu 3 Nen | 0xFF | 0x00 |
| Spy vs Spy | 0x21 | 0x13 |
| Seicross (v2) | 0x20 | 0x21 |
Seicross (v2) does not work with the above heuristic. However, the only difference between v1 and v2 of this game is the addition of this copy protection. Additionally, NES 2.0 submappers would handle it.
