nrom with chr ram

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.
Post Reply
coinheaven
Posts: 280
Joined: Sat Sep 17, 2005 12:26 pm

nrom with chr ram

Post by coinheaven »

is there any way to put a nrom rom with chr ram (instead of normal chr rom) on a normal nrom board?
tepples
Posts: 22708
Joined: Sun Sep 19, 2004 11:12 pm
Location: NE Indiana, USA (NTSC)
Contact:

Re: nrom with chr ram

Post by tepples »

I'm interested in the rewire instructions as well because RHDE needs this configuration (27C256 + 6264 CHR RAM).
FrankWDoom
Posts: 260
Joined: Mon Jan 23, 2012 11:27 pm

Re: nrom with chr ram

Post by FrankWDoom »

It should be possible the same way people do with FF3 repros or the various mmc5 repros that use ram instead of rom. If your rom is only 16K you might be able to cheat and use a UNROM board.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: nrom with chr ram

Post by lidnariq »

As long as the cartridge connector has the gold-plated finger for the CHR /WR signal, transplanting in an 6264 RAM is pretty easy.

But if it doesn't, you're probably better off getting an entirely new PCB made instead.
coinheaven
Posts: 280
Joined: Sat Sep 17, 2005 12:26 pm

Re: nrom with chr ram

Post by coinheaven »

huh? i think i tried to drop a chr ram chip in with no rewiring and it didnt work
lidnariq wrote:As long as the cartridge connector has the gold-plated finger for the CHR /WR signal, transplanting in an 6264 RAM is pretty easy.

But if it doesn't, you're probably better off getting an entirely new PCB made instead.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: nrom with chr ram

Post by lidnariq »

I didn't say "no rewiring", I said "pretty easy". The difference between a 28-pin 8KiB mask ROM, UVEPROM, EEPROM, and SRAM is ≈only the /WR strobe.

Looking at two boards (an NES-CNROM-256-05 and an NES-NROM-256-02) I have, PPU /WR has a gold plated contact, but no traces, so you'd need to remove the resist and solder a jumper of some sort in.
Last edited by lidnariq on Fri Dec 04, 2015 6:58 pm, edited 1 time in total.
User avatar
Memblers
Site Admin
Posts: 4044
Joined: Mon Sep 20, 2004 6:04 am
Location: Indianapolis
Contact:

Re: nrom with chr ram

Post by Memblers »

If it's like the MHROM boards I used when I made Garage Cart, you might have to cut a notch in the cart shell above the PPU /WR pin. Because the pin didn't fully extend to the inside part of the cart shell.
Post Reply