possible to convert TLSROM to TLROM?

A place that you can discuss reproduction of classic titles or "licensed-for-reproduction" homebrew for personal use.

Moderators: B00daW, Moderators

Forum rules
1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.
User avatar
FARID
Posts: 484
Joined: Wed Apr 07, 2010 1:14 am
Location: Iran
Contact:

Re: possible to convert TLSROM to TLROM?

Post by FARID » Thu Aug 11, 2016 10:22 pm

lidnariq wrote:You absolutely cannot run a TLSROM game on TLROM
I have seen mapper 118 game alongside with some other mapper 4 games inside of multicartridge :

Like this one :
http://cah4e3.shedevr.org.ru/cartsbase/JY-005.jpg
Turtles Fighters --> Mapper 4
Tiny Toon II --> Mapper 4
Goal II --> Mapper 118
Chip & Dale II --> Mapper 1

So they converted other games to mapper 118?

*********************

Also in this page : http://wiki.nesdev.com/w/index.php/INES_Mapper_118
Under $8001
for mirroring there is only one bit (M) but the Mirroring configuration counts up to 5!
How it is possible?
Maybe the mirroring is controlled with 7th and 6th and 5th bits?

*********************

Also according to iNES Mappers by Mapper Number v0.6.1 by Disch
The register for mirroring in 118 is the 7th bit of $8000, while in the nesdev wiki it is $8001, so the wiki correct and Disch is wrong?
Attachments
disch.PNG
disch.PNG (7.9 KiB) Viewed 2217 times
mapper118.PNG

lidnariq
Posts: 8785
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: possible to convert TLSROM to TLROM?

Post by lidnariq » Fri Aug 12, 2016 12:35 am

Given that JY-005 is undumped, per Санчез's status summary, I don't think there's any reason to assume that the hardware inside is strictly TLROM or TLSROM, or even MMC3-shaped, as opposed to something else altogether.

In mapper 118 (TxSROM), the game uses the CHR banks themselves to control mirroring. This means that:
• If the game wrote to $8000 with the $80s bit clear, then:
•• Possible layouts are either 1-screen or horizontal mirroring / vertical layout (because CHR bank $0000-$07FF is the same to the MMC3 as the nametables from $2000-$27FF)
• If the game wrote to $8000 with the $80s bit set, then
•• All layouts are possible, by writing some number to the four CHR banks in R2-R5. But you still have to keep the game from stepping on your now CHR-and-NT banking registers.

User avatar
HVC-Man
Posts: 41
Joined: Wed Nov 25, 2015 7:54 pm

Re: possible to convert TLSROM to TLROM?

Post by HVC-Man » Fri Aug 12, 2016 12:43 am

FARID wrote:I have seen mapper 118 game alongside with some other mapper 4 games inside of multicartridge :
You don't understand what is going on. You really should read what nametable mirroring is.

http://wiki.nesdev.com/w/index.php/Mirroring

The only difference between Mapper 4 and 118 is the nametable mirroring. That has to do with how the 2KB SRAM inside the FC/NES is arranged with graphics data. The MMC3 is normally not capable of single screen mirroring. The TLSROM / TKSROM board gets around that by hardwiring single screen mirroring mode, as in the MMC3 has no control over that. The MMC3 normally offers software-controlled horizontal and vertical mirroring.

This is easy to adjust in a pirate mapper, all that's needed is expanding upon the original MMC3 by adding that software control for single screen mirroring or the plain H/V mirroring.

In software, it's like opening a can of worms. Nametable mirroring is a HUGE part of how a game appears on the TV screen, namely ones that scroll or have things like sections of the screen devoted to health bars and the like. You can't easily make a H/V mirroring game work in single screen mirroring mode or vice versa. It's just not possible without a massive hacking effort. Just hack the board and call it a day.

lidnariq
Posts: 8785
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: possible to convert TLSROM to TLROM?

Post by lidnariq » Fri Aug 12, 2016 12:57 am

HVC-Man wrote:The TLSROM / TKSROM board gets around that by hardwiring single screen mirroring mode, as in the MMC3 has no control over that.
Er. Are you thinking of mapper 206 = Namco 108?

I know of precisely one game that uses hardwired single screen mirroring, and its mapper is not MMC3-shaped.

User avatar
HVC-Man
Posts: 41
Joined: Wed Nov 25, 2015 7:54 pm

Re: possible to convert TLSROM to TLROM?

Post by HVC-Man » Fri Aug 12, 2016 1:11 am

Allow me to re-phrase.

http://wiki.nesdev.com/w/index.php/INES_Mapper_118

" The CHR A17 line connects directly to CIRAM A10 line instead of MMC3's CIRAM A10 output, to compensate for the MMC3's lack of single-screen mirroring."

That sounds to me like the MMC3 doesn't have control over the mirroring. Sorry if my use of the word "hardwired" was confusing. I didn't realize it meant tying to 5v or gnd.

Post Reply