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Create support for Mapper 474 #565

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Akeraiotitasoft opened this issue May 11, 2023 · 0 comments
Open

Create support for Mapper 474 #565

Akeraiotitasoft opened this issue May 11, 2023 · 0 comments

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@Akeraiotitasoft
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Akeraiotitasoft commented May 11, 2023

https://www.nesdev.org/wiki/NES_2.0_Mapper_474

I've created a mapper that maps 0x4020 to 0xFFFF to PRG ROM.
I called it Akerasoft Mapper 474. This is NROM-383.
It maps more than NROM-368. But an NROM-368 is also planned.

My prototype uses FLASH memory but is designed to be programmed before soldering and is not reflashable.

https://www.nesdev.org/wiki/NROM-368

My design however is this 64KB of ROM space:
Bank 0:
Memory 0x0000 - 0x3FFF (empty or ignored, all zeros?)
Bank 1:
Memory 0x4000 - 0x041F (empty or ignored, all zeros?)
Memory 0x4020 - 0x7FFF (PRG)
Bank 2:
Memory 0x8000 - 0xBFFF (PRG)
Bank 3:
Memory 0xC000 - 0xFFFF (PRG)

Mapper 474 submapper 0 - 0x4020 - 0xFFFF (NROM-383)
Mapper 474 submapper 1 - 0x4800 - 0xFFFF (NROM-368)

@Akeraiotitasoft Akeraiotitasoft changed the title Create support for Mapper 472 Create support for Mapper 474 May 11, 2023
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