I'm making the BIOS for a custom SNES-OS, and I created a mapping to help me.
It supports 1GiB disks, and a partition size of only exactly 64MiB.
BIOS is stored on cartridge, and all other programs are transferred to cartridge WRAM through the disk (or flash).
WRAM has to be volatile.
The amount of WRAM stored in the cartridge is 263040KiB (256MiB+128KiB+768KiB).
00FC00-00FDFF: custom fncall address RAM
00FE00-00FEFF: BIOS fncall address ROM
00FF00-00FFAF: BIOS startup and interrupt ROM
00FFB0-00FFDF: Nintendo-compliant ROM header
400000-40FFFF: 128 mapper-selected disk/flash sectors
6FF800-6FFFFF: extra custom I/O (I'll document them in a seperate post)
700000-7BFFFF: 3 switchable blocks of static cartridge WRAM
7C0000-7DFFFF: unswitchable block of dynamic cartridge WRAM
FC0000-FFFFFF: BIOS main ROM
I'm sure this mapping is not supported by that many emulators. Is there any way I can copy this ROM image to a digital file?
Weird self-created mapping
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JHSHernandez-ZBH
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Weird self-created mapping
Last edited by JHSHernandez-ZBH on Wed Mar 12, 2025 12:43 am, edited 2 times in total.
Code: Select all
ldx #$00
lda $FF00,x
sta $00,x
inx
bne $F8
jmp $000D
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Oziphantom
- Posts: 1876
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Re: Weird self-created mapping
copy this ROM to a digital file?
You might be able to use Higan Manifests to map stuff https://higan.readthedocs.io/en/stable/ ... manifests/
You might be able to use Higan Manifests to map stuff https://higan.readthedocs.io/en/stable/ ... manifests/
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JHSHernandez-ZBH
- Posts: 4
- Joined: Mon Mar 10, 2025 12:38 am
- Location: Managing a teleporter in a universe-bridging skyscraper
Re: Weird self-created mapping
any way easily supported by emulators?
i don't have any, but it doesn't matter
i don't have any, but it doesn't matter
Code: Select all
ldx #$00
lda $FF00,x
sta $00,x
inx
bne $F8
jmp $000D
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Oziphantom
- Posts: 1876
- Joined: Tue Feb 07, 2017 2:03 am
Re: Weird self-created mapping
the manifest might let you set up the carts layout, but extra I/O commands are going to be "modify the emulator" territory. Maybe the LUA scripting systems will allow you to trap and handle them. you might be able to make your fake cart in LUA as well on Mesen, with the RAM and file I/O handled by LUA.
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JHSHernandez-ZBH
- Posts: 4
- Joined: Mon Mar 10, 2025 12:38 am
- Location: Managing a teleporter in a universe-bridging skyscraper
Re: Weird self-created mapping
well the I/O currently includes control for disk sector mapping, control for cartridge WRAM mapping, and an interrupt status register.
Code: Select all
ldx #$00
lda $FF00,x
sta $00,x
inx
bne $F8
jmp $000D