How to external IC to (re-)add CHR-RAM to a PCB

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How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-16 (#101269)
How to external IC to (re-)add CHR-RAM to a PCB?

I want to the CHR and chr-ram work together.

For example, some chinese privte cartridge.
http://wiki.nesdev.com/w/index.php/MMC3 ... nd_CHR_RAM
Re: How to external IC to (re-)add CHR-RAM to a PCB
by tepples on 2012-10-16 (#101272)
You'll need to build a decoder or comparator circuit that creates the enable signals for each chip depending on the bank address that the MMC3 outputs.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-16 (#101334)
tepples wrote:
You'll need to build a decoder or comparator circuit that creates the enable signals for each chip depending on the bank address that the MMC3 outputs.



I think so，but how to?
Re: How to external IC to (re-)add CHR-RAM to a PCB
by tepples on 2012-10-16 (#101336)
That depends. In the mapper you're trying to simulate, which banks are ROM and which banks are RAM? For example, in TQROM (#119), 64-127 and 192-255 are RAM.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-16 (#101346)
tepples wrote:
That depends. In the mapper you're trying to simulate, which banks are ROM and which banks are RAM? For example, in TQROM (#119), 64-127 and 192-255 are RAM.


At this time,it is diffcault for me .
Re: How to external IC to (re-)add CHR-RAM to a PCB
by tepples on 2012-10-17 (#101347)
Which mapper are you using? Is this for a new game, or are you trying to reproduce an existing Chinese game? Which game?
Re: How to external IC to (re-)add CHR-RAM to a PCB
by socram8888 on 2012-10-17 (#101362)
If you're having difficulties writting in English, try writting in your native language. There are people from all the world, I'm sure there's somebody here who can understand and help you.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-17 (#101368)
tepples wrote:
Which mapper are you using? Is this for a new game, or are you trying to reproduce an existing Chinese game? Which game?


I want to make mapper 19x(191,192,194,198,199)!
I try to hack these rom(mapper) to mmc5 and flash to mmc5 cartridge.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-17 (#101374)
tepples wrote:
Which mapper are you using? Is this for a new game, or are you trying to reproduce an existing Chinese game? Which game?


Mapper 198 is base on MMC3!
Mapper198 has more than 512k PRG (640K),no CHR
And have a exram at 5000~5FFF!
Maybe MMC3 can improve （add exram and up to 1024K PRG）
Re: How to external IC to (re-)add CHR-RAM to a PCB
by infiniteneslives on 2012-10-17 (#101376)
byemu wrote:
Mapper198 has more than 512k PRG (640K),no CHR
And have a exram at 5000~5FFF!
Maybe MMC3 can improve （add exram and up to 1024K PRG）


Putting RAM there doesn't automatically make it EXRAM in the spirit of MMC5. It's not going to have PPU attribute characteristics, just 4KB of more RAM located at the same place as MMC5's EXRAM. You'll have to use your own circuit (outside of the MMC3) to place RAM there anyways.

If you had *NO* CHR (or 2KB or less) you could use all 7 bits (CHR ROM A11-17) to have 64MB of PRG.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by lidnariq on 2012-10-17 (#101377)
If I'm understanding byemu correctly, he has a mapper 198 game ("waixing type f", according to nestopia) and wants to put it on a cartridge that uses MMC5 instead.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-17 (#101378)
lidnariq wrote:
If I'm understanding byemu correctly, he has a mapper 198 game ("waixing type f", according to nestopia) and wants to put it on a cartridge that uses MMC5 instead.


Yeah!
Also wants to put it on a cartridge that uses MMC3 instead.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by infiniteneslives on 2012-10-17 (#101380)
well I'm thoroughly confused as to the actual goal here...

Is this for an original game or homebrew? sounds like both???
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-17 (#101382)
infiniteneslives wrote:
well I'm thoroughly confused as to the actual goal here...

Is this for an original game or homebrew? sounds like both???



I have many projects to research！
* up MMC3 prg(cartridge not include chr) to 1024 or more
* add ExRam to 5000~5FFF(same as "http://wiki.nesdev.com/w/index.php/PRG_RAM_circuit",but different address)
* adn an chr-ram to a cartridge(the cartridge has the chr rom)
These items are used in different occasions！
Re: How to external IC to (re-)add CHR-RAM to a PCB
by lidnariq on 2012-10-18 (#101383)
byemu wrote:
* up MMC3 prg(cartridge not include chr) to 1024 or more
Could be done by either repurposing CHR banking bits (like mapper 245) or replacing PRG-RAM with a register that swaps 512KB blocks (similar to mapper 47)

Quote:
* add ExRam to 5000~5FFF(same as http://wiki.nesdev.com/w/index.php/PRG_RAM_circuit, but different address)
You could use the '139-based plan listed there, and replace 1/E←A13 and 2A0←A12.

Quote:
* add an chr-ram to a cartridge(the cartridge has the chr rom)
The description on the wiki for TQROM describes the simplest way of doing it (128KB for ROM, 128KB window for RAM)
Re: How to external IC to (re-)add CHR-RAM to a PCB
by byemu on 2012-10-18 (#101384)
lidnariq wrote:
repurposing CHR banking bits (like mapper 245)

It's a good idea to visit more than 512k prg!
A19 connect to the CHR A??
Code:
Init high 512k bit
lda #$0
sta $8000
lda #$2
sta $8001

then
lda #$6 or 7
sta $8000
lda #$XX
sta $8001

bank the high 512k

but can't direct bank the high bank like:
Code:
lda #$6 or 7
sta $8000
lda #$40
sta $8001



lidnariq wrote:
replacing PRG-RAM with a register that swaps 512KB blocks (similar to mapper 47)

Is similar to mapper245?

lidnariq wrote:
You could use the '139-based plan listed there, and replace 1/E←A13 and 2A0←A12.

Good idea ,I'll try this way.

lidnariq wrote:
The description on the wiki for TQROM describes the simplest way of doing it (128KB for ROM, 128KB window for RAM)


I think i need more information and the details to do this.
Re: How to external IC to (re-)add CHR-RAM to a PCB
by lidnariq on 2012-10-18 (#101390)
byemu wrote:
lidnariq wrote:
repurposing CHR banking bits (like mapper 245)

It's a good idea to visit more than 512k prg!
A19 connect to the CHR A??
Code:
Init high 512k bit
lda #$0
sta $8000
lda #$2
sta $8001

then
lda #$6 or 7
sta $8000
lda #$XX
sta $8001

bank the high 512k

Unfortunately it's not that simple. You'll either need to write the same value to all 6 CHR banking registers, or give up mapper controlled mirroring and interrupts with a true MMC3.

Quote:
but can't direct bank the high bank like:
Code:
lda #$6 or 7
sta $8000
lda #$40
sta $8001

If you want that you'll need to find someone's generic clone or make your own in a CPLD.

byemu wrote:
lidnariq wrote:
replacing PRG-RAM with a register that swaps 512KB blocks (similar to mapper 47)

Is similar to mapper245?
No? It's similar to mapper 47, and maybe to mappers 44, 45, 52, and 205.

byemu wrote:
lidnariq wrote:
The description on the wiki for TQROM describes the simplest way of doing it (128KB for ROM, 128KB window for RAM)
I think i need more information and the details to do this.
I don't know how to make it more clear.