completing iNES mappers

Discuss emulation of the Nintendo Entertainment System and Famicom.

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aquasnake
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completing iNES mappers

Post by aquasnake »

This is an overview of my ines implementation. A few are not supported. Due to the lack of information, the wiki does not describe them

Mapper54 seems to have been reassigned in NES 2.0, but this iNES number is used as a private mapper by some emulators

Mapper60, based on reset switching, is just a combination of four NROMs. I have reservations about whether it can be regarded as a mapper. It is also used by some emulators as their private mapper.

Mapper230, which is a combination of mapper226 and UNROM and is based on reset switching, should actually be a duplicate of mapper226. Which is an early method to combine in the most brutal way.

Mapper233, the wiki description here may be wrong, and all game mirrorings in it can only be horizontal or vertical. Therefore, if it is assumed that the logical data is obtained by testing the damaged hardware, it is likely that the mirroring bit description is wrong. Despite this, it is a duplicate of mapper226
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NewRisingSun
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Re: completing iNES mappers

Post by NewRisingSun »

Mapper 54 is basically a bad mapper assignment and can be freed for reallocation. No game or multicart in nes20db uses it.

There are several reset-based multicarts, mapper 60, mapper 313, and mapper 374. Mapper 60 has been allocated in the last century, and I see no reason to reopen the debate on whether those should be regarded true mappers or not.

I do not see why 233 should be a duplicate for 226. 226 has two registers in the $8000-$FFFF range, 233 just one.
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aquasnake
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Re: completing iNES mappers

Post by aquasnake »

In China/Russia/Brazil, there are a huge number of reset-based pirate carts, and some people are constantly making them nowadays. The ROM number of those multicarts is not uniform, usually from 4-in-1 to 16-in-1. The switching mode and the counter accumulation principle are different.

If you count these massive carts, I'm afraid the NES 2.0 database will increase explosively, There are not enough allocation spaces in NES2.0 for them.
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aquasnake
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Re: completing iNES mappers

Post by aquasnake »

if you remove the prg rom from a mapper233's board to a mapper226 one, i'm pretty sure it works fine :D
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Ben Boldt
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Re: completing iNES mappers

Post by Ben Boldt »

I made my own reset based carts years ago. I also made carts with dip switches. The reset based ones just eliminate the physical switches but have the same function. These carts can have any base mapper. I was collecting different mapper carts and making the applicable games selectable this way. I don’t consider the reset part of the mapper. They share the same “base” mapper. Actually not all the games are the same size so I got clever allocating all the space in some cases. Zillions of unpredictable combinations might exist this way. Pretty silly to think I should be able to emulate the whole thing at once and not each individual game.

I think the better solutions for these kludgey carts is to just have separate dumps for each game and put them all in a folder together. Name the folder whatever the cart is called. That makes the most sense to me.
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aquasnake
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Re: completing iNES mappers

Post by aquasnake »

The reset switch circuit can be combined with any mapper. In a more understandable way, this part of the circuit can be isolated from the mapper, and the hardware can also be made on an adapter board, like the GameGenie

Generally, it provides the upper bit of the address lines (e.g. 4 bits if it is 16-in-1) and drives the PRG and CHR ROM address lines together

Because the basic capacity of PRG and CHR is different, the combination formula between them can be:

(prg+chr)*n

prg = 16, 32,64, 128, 256...
chr = 8, 16, 32, 64...
n = 2,4,8,16...

You can also switch the state machine after each reset(i.e. mapper switching)
NewRisingSun
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Re: completing iNES mappers

Post by NewRisingSun »

aquasnake wrote:if you remove the prg rom from a mapper233's board to a mapper226 one, i'm pretty sure it works fine
I did, and no, it does not.
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aquasnake
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Re: completing iNES mappers

Post by aquasnake »

NewRisingSun wrote: Thu Jan 13, 2022 12:41 am
aquasnake wrote:if you remove the prg rom from a mapper233's board to a mapper226 one, i'm pretty sure it works fine
I did, and no, it does not.
Would you like to post the rom here?

I'm interested in testing.
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