SimCity prototype found!

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Banshaku
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Re: SimCity prototype found!

Post by Banshaku » Thu Dec 27, 2018 8:34 am

I have one devcart somewhere but I never used it (I think I did prepare the sockets for the flash eeprom). I will have to check someday if it's compatible with it.

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dougeff
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Re: SimCity prototype found!

Post by dougeff » Thu Dec 27, 2018 12:36 pm

Someone told me that the game was only 50% complete.

Are we sure that the game is even fully playable?
Last edited by dougeff on Thu Dec 27, 2018 12:45 pm, edited 1 time in total.
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Re: SimCity prototype found!

Post by tepples » Thu Dec 27, 2018 12:42 pm

Are there stretches of mostly 6502 code without the new 65816-specific instructions (STZ, INC A, etc.) in the Super NES version of SimCity, Tetris & Dr. Mario, Yoshi's Cookie, or Wario's Woods? I ask because it might point at practices of sharing code between the NES and Super NES versions of a game.

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Re: SimCity prototype found!

Post by lupin3rd » Thu Dec 27, 2018 12:44 pm

dougeff wrote:Someone told me that the game was only 50% complete.

Are we sure that the game is even playable?
My understanding is that there was a bug that prevented the game from being completed. I also understood this to be an incomplete prototype that had lots of unused graphics (unimplemented, I believe) for the build. The news that is spreading says that someone had disassembled the prototype and commented the code pretty extensively, and I believe fixed a couple of bugs along the way. Not sure where that leaves the playability though.
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lidnariq
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Re: SimCity prototype found!

Post by lidnariq » Thu Dec 27, 2018 12:45 pm

Playable, yes: I can place zones and have them develop, traffic is simulated, &c.

Complete? Definitely not. There's an education overlay but no education zones. Residential zones seem to only have the "low density" form. There's plenty of other missing things. Several scenarios just don't work (Bern)

The archive.org download includes reverse engineering notes from (pretty certain) Санчез, which includes a very large "unfinished" section. (Certainly the actual disassembly is marked as his)

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dougeff
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Re: SimCity prototype found!

Post by dougeff » Thu Dec 27, 2018 1:18 pm

Санчез

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raldi
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Re: SimCity prototype found!

Post by raldi » Sun Dec 30, 2018 10:35 am

Looking at the video, I don't understand how the metatiles and palettes could have worked: Most types of construction are 16x16 pixel squares, but they can be aligned to any 8-pixel boundary. You'd think that would lead to Marble-Madness-style attribute leaking alongside adjacent tiles, but I don't see any evidence of that. Anyone know (or want to venture a guess) as to how they did it?

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toggle switch
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Re: SimCity prototype found!

Post by toggle switch » Sun Dec 30, 2018 10:48 am

wouldn't be surprised if it used a board with 8x8 attributes.

edit - yup, it's on MMC5

GreyRogue
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Re: SimCity prototype found!

Post by GreyRogue » Sun Dec 30, 2018 12:46 pm

Greg2600 wrote:Argh, MMC5! Won't work on a flash cart.
I've got it working in MiSTer (FPGA) in my fork (MMC5 mapper originally written by Ludvig Strigeus, I believe, with a few fixes from me). It uses a few flags it gets directly from the NES core, which will need to be translated for a flash cart, but it should be doable.
If the source for an existing MMC5 flash cart mapper is available, it shouldn't be too hard to fix.

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getafixx
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Re: SimCity prototype found!

Post by getafixx » Sun Dec 30, 2018 1:05 pm

GreyRogue wrote: If the source for an existing MMC5 flash cart mapper is available, it shouldn't be too hard to fix.
Krikzz released his MMC5 mapper source a while back for the EverDrive N8 cart.
Attachments
mmc5-src.zip
Krikzz MMC5 mapper source
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Re: SimCity prototype found!

Post by lidnariq » Sun Dec 30, 2018 6:57 pm

GreyRogue wrote:It uses a few flags it gets directly from the NES core, which will need to be translated for a flash cart, but it should be doable.
Out of curiosity, what?

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Re: SimCity prototype found!

Post by GreyRogue » Sun Dec 30, 2018 9:58 pm

lidnariq wrote:
GreyRogue wrote:It uses a few flags it gets directly from the NES core, which will need to be translated for a flash cart, but it should be doable.
Out of curiosity, what?

Code: Select all

// unpack ppu flags
  wire ppu_in_frame = ppuflags[0];
  wire ppu_sprite16 = ppuflags[1];
  wire [8:0] ppu_cycle = ppuflags[10:2]; 
wire [8:0] ppu_scanline = ppuflags[19:11];
sprite16 can be sniffed from writes. The others are doable, but a little harder.

Some of the things it does:
It uses external attributes and external nametables, but it uses the nametables interface to get data into and out of the ExRAM whether or not the data is actually nametable data. So for the title screen, it sets it for nametable mode, then uses the PPUADDRESS/DATA (2006/7) to write data to the ExRAM. It then reads back data from the 2006/7 area and writes it to different addresses for sections that are the same. All of this data for the title screen is actually external attribute data, not nametables, though, so it switches to that mode before it starts rendering it. So all of the ExRAM stuff needs to to work correctly for the graphics to show correctly. Why it didn't just use the 5C00-5FFF range instead...I don't know.

GreyRogue
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Re: SimCity prototype found!

Post by GreyRogue » Mon Dec 31, 2018 1:56 am

getafixx wrote:
GreyRogue wrote: If the source for an existing MMC5 flash cart mapper is available, it shouldn't be too hard to fix.
Krikzz released his MMC5 mapper source a while back for the EverDrive N8 cart.
Unless I'm just not seeing it, I don't see where the Extended RAM attributes are handled. The game uses these. Graphics will be corrupted without them.

Greg2600
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Re: SimCity prototype found!

Post by Greg2600 » Mon Dec 31, 2018 5:55 pm

I just tried it [V20 rc6] and it seems very playable. The first few title screens are garbled but the game itself runs fine. How "finished" is it? I'm not sure, but it definitely seems to function as the original PC game did.

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Re: SimCity prototype found!

Post by zeroone » Thu Jan 03, 2019 1:08 pm

It looks like the SimCity prototype exposed some issues with Nintaco's MMC5 mapper. It works until you start playing. Then the displayed map area is garbled.

Does the prototype tap into some MMC5 feature not used by the other commercial games? Like the Wiki suggests, I probably just coded enough features to get the other MMC5 games working.

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