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PostPosted: Fri Sep 01, 2017 1:41 pm 
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Yeah, you could use /RAM1CE as A15, and AND(/RAM1CE,/RAM2CE) as /BiggerRAMCE, if you could get your hands on a ≥64 KiB SRAM.

But NES-ETROM is already nicely set up for this upgrade (SL15/CL15), and I'm pretty certain it'd be easier to piggy-back an extra RAM onto NES-EWROM.


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PostPosted: Fri Sep 01, 2017 1:54 pm 
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ideally yeah. but if I ever have the option to make a cart out of this, I'd rather not sacrifice a NES ETROM cart for reasons of cost and ruining something I'd otherwise collect. so it's down to modifying a lesser board, or famicom carts.


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PostPosted: Fri Sep 01, 2017 2:09 pm 
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rainwarrior wrote:
SNES SimCity had 256k RAM inside it, for comparison, which could save two cities, so that might put an assumption for 64k WRAM being necessary into perspective.

SimCity (Super NES) battery RAM is 256 kbit, same as SXROM/EWROM. (Source: SnesCartDB)


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PostPosted: Fri Sep 01, 2017 3:55 pm 
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lidnariq wrote:
The pictures of the PCB (in the cut up gold shelled prototype) show a NES-ETROM board with two RAMs, both socketed.

I'm guessing that's an ETEPROM board, rather than an ETROM that they socketed. So, not necessarily bigger than 2x8k. That photo came from an old eBay auction for a Laser Invasion proto, btw.


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PostPosted: Fri Sep 01, 2017 4:06 pm 
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Oh, fair enough.


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PostPosted: Fri Sep 01, 2017 4:47 pm 
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tepples wrote:
SimCity (Super NES) battery RAM is 256 kbit

Thanks for the correction (and the helpful link to an SNES cartridge database).


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PostPosted: Fri Sep 01, 2017 6:46 pm 
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The SNES has 128KB of onboard RAM, so the entire cartridge RAM can be dedicated to save data. On the NES it's most likely that one of the two cartridge RAMs is work RAM and the other is save data, just like all the Koei games.

FrankWDoom wrote:
ideally yeah. but if I ever have the option to make a cart out of this, I'd rather not sacrifice a NES ETROM cart for reasons of cost and ruining something I'd otherwise collect. so it's down to modifying a lesser board, or famicom carts.


Out of the MMC5 PCBs that support any WRAM, ETROM is the most common. EKROM and EWROM are only used by one US game each (Gemfire and ROT3KII respectively); ETROM is used by four (Bandit Kings of Ancient China, L'Empereur, Nobunaga's Ambition II and Uncharted Waters)


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PostPosted: Fri Sep 01, 2017 7:02 pm 
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On ELROM, you could piggy-back a 32-pin 128Ki x 8 SRAM on top of (or underneath) the existing PRG-ROM, without too many random bonus wires... but it is an awful lot of fiddly rework, including a good deal of SMT work to get to the pins on the MMC5 that aren't broken out.


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PostPosted: Sat Sep 09, 2017 3:29 pm 
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maseter wrote:
there is an open-source city-building game for the GBC:
[...]
Get this "µCity 1.0" for free here: https://github.com/AntonioND/ucity

It's telling that this is GBC exclusive for the same reason that SimCity would have been expensive to replicate: it needs a comparative ton of work RAM.


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PostPosted: Tue Sep 26, 2017 6:50 am 
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So do we know if anyone has tried to get in touch with the person to see about dumping the game? Other than wanting to try game myself like most everybody else here, I'd REALLY hate to see it eventually lost forever if the eproms finally give out and it was never dumped.


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