NES 2.0 Mapper 298: Difference between revisions
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[[Category:Mappers with cycle IRQs]] | {{DEFAULTSORT:298}}[[Category:Mappers with cycle IRQs]] | ||
NES 2.0 Mapper is used for the unlicensed game ''Lethal Weapon'', which is actually a backport of [https://en.wikipedia.org/wiki/Lethal_Enforcers Lethal Enforcers]. Its UNIF board name is '''UNL-TF1201'''. | '''NES 2.0 Mapper 298''' is used for the unlicensed game ''Lethal Weapon'', which is actually a backport of [https://en.wikipedia.org/wiki/Lethal_Enforcers Lethal Enforcers], and not to be confused with the [http://bootgod.dyndns.org:7777/profile.php?id=702 licensed game of the same name]. Its UNIF board name is '''UNL-TF1201'''. | ||
The board uses a [[VRC4]] clone in the VRC4b configuration (CPU 0x02s to VRC4 A0, CPU 0x01s to VRC4 A1). The only difference is that register $F003 is | The board uses a [[VRC4]] clone in the VRC4b configuration (CPU 0x02s to VRC4 A0, CPU 0x01s to VRC4 A1). The only difference is that register $F003 is implemented differently than on the original ASIC: writing to $F003 only acknowledges a pending IRQ, but it does not move the 'A' control bit to the 'E' control bit [[VRC IRQ#IRQ_Acknowledge|the way an original VRC4 does]]. This is relevant for emulation, as the game writes to $F003 immediately after enabling the IRQ by writing $02 to $F002. | ||
The level selected by the middle icon in the top row of the level selection screen [https://youtu.be/YIdkWZuoRXM will shake greatly on real hardware], and therefore is not an emulation fault. | |||
Latest revision as of 18:32, 29 May 2020
NES 2.0 Mapper 298 is used for the unlicensed game Lethal Weapon, which is actually a backport of Lethal Enforcers, and not to be confused with the licensed game of the same name. Its UNIF board name is UNL-TF1201.
The board uses a VRC4 clone in the VRC4b configuration (CPU 0x02s to VRC4 A0, CPU 0x01s to VRC4 A1). The only difference is that register $F003 is implemented differently than on the original ASIC: writing to $F003 only acknowledges a pending IRQ, but it does not move the 'A' control bit to the 'E' control bit the way an original VRC4 does. This is relevant for emulation, as the game writes to $F003 immediately after enabling the IRQ by writing $02 to $F002.
The level selected by the middle icon in the top row of the level selection screen will shake greatly on real hardware, and therefore is not an emulation fault.
