Issue trying to make Mega Man Origins

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AaronE
Posts: 28
Joined: Mon Jan 21, 2013 7:25 pm

Issue trying to make Mega Man Origins

Post by AaronE »

I took a NES ELROM board and removed the PRG and CHR ROM.
I patched a copy of megaman 1 per the readme and the resulting patched rom plays ok on an emulator.
I removed the header and burned it to an AM27C040-120DC, installed that eprom and rewired pins 1,2, 24,30 and 31.

I installed some 62256 RAM in place of the CHR-ROM (Sony CXK58256P-10L), installed it offset pin 1 to maskrom hole 3 alignment, and rewired it:
Pin 1 to hole 29 (A14)
Pin 22 (OE) to hole 31 (/CE)
Pin 27 (/WE) to Pin 56 on the NES cart (PPU /WR)
Pin 28 to Pin 32 (Vcc, +5V)

The resulting game boots but I get alternating horizontal lines in the screen at the title screen and the colors in the game are off.

Any ideas on where I might be off?
guitarzombie
Posts: 164
Joined: Sat Dec 07, 2013 6:18 pm

Re: Issue trying to make Mega Man Origins

Post by guitarzombie »

You might have done everything right, but just doesn't work on real hardware as well as it does on an emulator. I think thats usually the case for mmc5 games
Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

Re: Issue trying to make Mega Man Origins

Post by Ice Man »

Game works fine on hardware, but like I just PMed him.
MM Origins is 512kb in size and ELROM only supports up to 256kb.
Besides, MM Origins has 8kb PRG-RAM from what I could find and the only proper donor would be a ETROM board. :)
guitarzombie
Posts: 164
Joined: Sat Dec 07, 2013 6:18 pm

Re: Issue trying to make Mega Man Origins

Post by guitarzombie »

Oh i didnt look into it THAT far haha.

BTW MMC5 supports 1 meg of PRG and CHR
AaronE
Posts: 28
Joined: Mon Jan 21, 2013 7:25 pm

Re: Issue trying to make Mega Man Origins

Post by AaronE »

Yeah I don't understand why this NES-ELROM board doesn't support > 256kb (it's laser invasion).
If anyone knows the reason I'd love to know just to see if it can be gotten around.

The wiki says they go up to 1024.
http://wiki.nesdev.com/w/index.php/ExROM
tepples
Posts: 22708
Joined: Sun Sep 19, 2004 11:12 pm
Location: NE Indiana, USA (NTSC)
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Re: Issue trying to make Mega Man Origins

Post by tepples »

It can be worked around: wire the appropriate MMC5 output pins to the appropriate lifted pins on the PRG ROM.
AaronE
Posts: 28
Joined: Mon Jan 21, 2013 7:25 pm

Re: Issue trying to make Mega Man Origins

Post by AaronE »

A18 and A19, MMC5 65 and 66, have continuity to the PRG spot by default. Any idea what line would be missing?

In fact, A19, A18, A17 and A16 all have continuity back to the correct pins on the MMC5.
Pin 22, /CE, doesn't have connection to the MMC5 chip but is instead directly connected to cart pin 1 (ground)
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