It is currently Sat Oct 20, 2018 8:18 am

All times are UTC - 7 hours





Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Sat Mar 05, 2005 8:35 pm 
Offline

Joined: Tue Nov 23, 2004 9:35 pm
Posts: 702
I have heard that making a NES Flash Cart is such a big problem because of the great number of memory mappers. But if you look at licensed games, three memory mappers stand out, the MMC1 and MMC3/MMC6 and the '161 based mappers (whihc includes no mapper). Consider a cartridge with the following specs:

512KB of PRG-ROM
256KB of CHR-ROM
16KB of CHR-RAM
16KB of W-RAM (with battery)
4KB of V-RAM

With a cart you could handle all the MMC1 and MMC3/MMC6 games that required CHR-RAM or CHR-ROM. You could also handle battery backed games. The CHR-RAM could be used in the '161 mappers that require it (A, B ,C, U*ROMs). The CHR-ROM would be used in the '161 mappers that require it (G, M, R and NROMs).

What couldn't this cart do? Well, it won't be able to handle MMC2, MMC5 or Sunsoft FME-1 games. That is 11 licensed games, most of them Koei strategy games ( and you consider the two versions of Punch-Out separate games.) It can also handle several of Tengen and Camerica's games, and the majority of AVE and Color Dreams/Wisdom Tree/Bunch Games could also be supported without greatly adding to the controller.

Here is how I envision the cartridge to look like. There will be four RAM chips on board. One will be for the PRG, a second for the CHR (whether RAM or ROM) a third will be for the W-RAM (with replaceable battery) and the fourth will be V-RAM for 4-screen mirroring. The games themselves would be downloaded from a USB2 cable or stored on a stick of flash memory that attaches to the cart. The controller chip should stand in between the RAM chips and the cartridge connector to handle those cartridges that have unusual ROM wiring.

If anyone thinks that this is too difficult, I have five words for them: Cuttle Cart 1 and 2.


Top
 Profile  
 
PostPosted: Sat Mar 05, 2005 11:23 pm 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 20678
Location: NE Indiana, USA (NTSC)
Great Hierophant wrote:
Consider a cartridge with the following specs:

512KB of PRG-ROM
256KB of CHR-ROM
16KB of CHR-RAM
16KB of W-RAM (with battery)
4KB of V-RAM

Why would you need both 16 KB of CHR RAM and 4 KB of VRAM (which I assume holds the map in 4-screen games)? Couldn't you just use one 16 KB chip and then assign $0000-$1FFF and $2000-$2FFF from that same chip?


Top
 Profile  
 
 Post subject:
PostPosted: Sun Mar 06, 2005 1:08 am 
Offline
Site Admin
User avatar

Joined: Mon Sep 20, 2004 6:04 am
Posts: 3569
Location: Indianapolis
Stripped down, compared to what? A cart like this would be fairly advanced, heheh. :)

The VGWiz Maxicart would be something similar, I suggested a design pretty much like this one. I'm not sure if it's still being worked on at all, or with CHR-ROM and MMC3 support.

I think tepples is right, one CHR-RAM chip would work just as well. SRAMs smaller than 32kB tend to be more expensive these days, anyway. Not a big difference, really.

I know I'd love to make a cart like this. I still need to learn how to use programmable logic in practice (I've got the theory down, for using schematic entry with Altera chips at least), and I planned on learning that stuff properly after I get Squeedo and some other projects finished up and distributed. Or I'd be happy to team up with someone who could do some parts of it.. I like doing PCBs 'n stuff, it's interesting work.

I'm sure someone will beat me to it though.

But a cart like this wouldn't be cheap to make. Look at how the Cuttle Cart ordering/distribution went, for example. I think you had to pre-order them to get one. Maybe some people don't mind that, but it could be an uncomfortable way to handle it. Though if everything goes perfectly, very convenient for the cart builder.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 07, 2005 11:13 pm 
Offline

Joined: Tue Nov 23, 2004 9:35 pm
Posts: 702
Stripped down compared to some vaporware "all mapper" cartridge. While I don't mean to impunge Kevin Horton's groundbreaking work on his console, but I don't know whether you could fit all the device(s)on a single cartridge. Besides This cart would handle the basics and a lot more but would be a disciplined three-pronged design. It would have the advantage of working with the mappers that have been documented the best.

Handling of this cart would be tricky. Proper notice would have to be made in all the big or targeted forums, AtariAge, Digital Press, Cherryroms, NESWorld, this one, etc. An ordering form would need to be set. A set number of persons would have to pledge themselves.

Is there a way to use one 32KB S-RAM chip as half CHR-RAM and half W-RAM? RAM is RAM and a chip should be able to map it as it pleases transparent to the NES or the game. That would decrease the PCB complexity. Also, as the 4-screen games use CHR-ROM the ordinarily unused RAM can be made to do something productive.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Mar 08, 2005 12:08 am 
Offline
Site Admin
User avatar

Joined: Mon Sep 20, 2004 6:04 am
Posts: 3569
Location: Indianapolis
Yeah, I see what you mean about the mapper support. But I think mappers like MMC3 sit somewhere between the ultra-cheap and more expensive solutions.. not sure where exactly. But it's possible that "could support MMC3" to "could support almost any mapper" wouldn't be too huge of a leap. (but not in terms of amount of work going into the firmware, heh)

One RAM chip normally can't be used by both PRG and CHR, since they're seperate buses. Maybe with some kind of fast buffer, but this becomes more useful for other things rather than simplifying the design, heheh.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group