simple dev cart for Famicom?

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ninja_kun
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Joined: Fri Jun 17, 2022 5:02 am

simple dev cart for Famicom?

Post by ninja_kun »

Hi all.

I bought an old Famicom and a Family Basic with a keyboard on a whim, and have been enjoying the rabbit hole that is getting it working, playing old games, buying cartridges, emulators etc. The wiki is very useful, and I've started experimenting with C and neslib. Seems like a great community here. So much knowledge, and the annual competition looks like fun.

I write software for a living, but new to hardware. Lots to learn. So, my question: what's a cheap and convenient way to be able to run a game on real hardware as you develop it?

I'm thinking some kind of dev cartridge with ROM for a bootloader, RAM mapped to most of PRG and all of CHR, and serial via the controller port to connect to my PC via USB? At this stage I'm just working within the limits of NROM, so it doesn't need to support complex mappers.

I'm even considering trying to draw up a PCB myself (first time), but if there is a nice board which already exists, I'd probably prefer that. I'm new at soldering, but could probably manage to assemble something myself, as long as it has nice big pin spacing.

Or maybe even just a board which adapts the edge connector into something I could wire to a breadboard more easily? :mrgreen:

Thanks in advance.
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rainwarrior
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Re: simple dev cart for Famicom?

Post by rainwarrior »

The Everdrive N8 has a famicom form. Otherwise the NES version, or a PowerPak can be used with a simple adapter for Famicom. Those are probably the easiest and most convenient ways to get software running on a Famicom. The Everdrive can be loaded via SD card or USB, the PowerPak via CF card.

A little harder might be to get pre-made PCBs from Muramasa Entertainment, put sockets on them and use EPROMs. There might be a flash variation that allows you to program an EEPROM on-board instead of having to use sockets, but I don't think I've seen a ready-made one for Famicom.

InfiniteNESLives (and commonly through the NES Maker project) was selling a flashable board for NES along with a USB flashing device. I don't know if there was ever a Famicom version but you can use the cart with an adapter.

Otherwise boards like that are fairly easy to customize with bodge wires or whatever. You can make your own boards, too, but unless there's something specific you need in that respect probably existing ones will save a lot of effort, at least in small quantities. (Game-Tech is a third source I know of for NES boards, but again needs an adapter for Famicom.)

A different alternative is the FDS Stick, which replaces the FDS' disk drive and connects directly to its RAM adapter. That gives you 32k of PRG-RAM and 8k of CHR-RAM to play with by loading FDS disk images via USB. Disk images Disk images are a less common format for Famicom software, but this is maybe cheap and convenient if you already have an FDS.
ninja_kun
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Re: simple dev cart for Famicom?

Post by ninja_kun »

Thank you for the detailed reply! That's very helpful.

The Everdrive N8 looks perfect, but a bit out of my price range, especially with the $US being what it is at the moment :( If my budget was in that ballpark though, it would do exactly what I want.

I think the NESMaker option with an adapter might be a winner at the price.

I did actually buy some Muramasa boards. Great price, and they look very nice. I was thinking to bodge one up as you suggested, but it's a bit of a shame that they are totally undocumented. A schematic would be ideal. I tried following the traces and beeping it out, but it's fairly painstaking with all the pads for selecting different options. In hindsight, I should have bought the simple NROM only cart, but I bought ones which support multiple mappers.

FDS stick sounds like exactly what I want too, but unfortunately mine is a regular AV Famicom, not an FDS. Might be a good excuse to buy an FDS though :D

Thanks again for all the great info!
Pokun
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Re: simple dev cart for Famicom?

Post by Pokun »

The Everdrive N8 is very cheap for what it is (an all-in-one solution flashcart mainly for playing games on but also great for developers). It supports most mappers including many obscure pirate mappers. The newer N8 Pro is quite expensive though but has some cool new features like an audio amplifier which makes expansion audio games possible (on the original N8 expansion audio volume is too low) and also bigger RAM for a few unlicensed games that uses very large ROMs.

But as a developer it's nice to have a simpler dev-cart for slapping on some EPROMs on (you need to cut a hole in the cartridge shell to fit slotted ROM chips though). Most of my homebrew (very simple stuff) uses NROM, and it's the most useful board type for quick and dirty testing really. UxROM and CNROM are great too since they don't need any custom chips and covers most of your needs.
Muramasa said long ago that he was gonna fix tutorials but it looks like he hasn't done that yet and now there are more advanced boards since that.
Which Muramasa board did you get?

The Twin Famicom requires special adapters if you want to use the built-in disk drive or RAM Adapter with the FDSStick, so not having a Twin isn't really bad news.
For the FDSStick you technically don't even need the disk drive since it works just with the RAM Adapter which can be bought separately and quite cheaply on ebay or so, I hardly use my disk drive anymore since I got the FDSStick, it allows me to store my precious save files somewhere safe, and with the right adapter it can also dump disks (including the save files).
The FDSStick is cheap and should have 100% compatibility with disk games so there are almost no reason not to pick one up. Though I understand the urge to have both the disk drive and the RAM Adapter. :)
ninja_kun
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Re: simple dev cart for Famicom?

Post by ninja_kun »

Sorry for the very late reply, somehow I missed your response!
But as a developer it's nice to have a simpler dev-cart for slapping on some EPROMs on (you need to cut a hole in the cartridge shell to fit slotted ROM chips though).
Yes, this is exactly what I'm looking for. Mostly NROM, and maybe UxROM. I already have a cheap USB ROM programmer. One issue is that I struggled to find 28-pin ROM chips, so I went with 32-pin flash chips instead. I'd like a board with sockets if possible, preferably tall enough to clear the cartridge slot. And supporting 32-pin chips by tying the extra address lines low or just leaving them floating. I've wired up a prototype on a breadboard (PRG only) and it works great.. Maybe I should try and turn it into a PCB and get some printed online, although I've never made a PCB before..
Which Muramasa board did you get?
I got the FC discrete boards. In hindsight, I kind of wish I'd gone with the NROM only ones. FC discrete would be great if there were clear instructions for each mapper type though. The price and quality of the boards is very nice though in my opinion.
The FDSStick is cheap and should have 100% compatibility with disk games so there are almost no reason not to pick one up.
Thanks, this is great info! I will look into this.
The Everdrive N8 is very cheap for what it is (an all-in-one solution flashcart mainly for playing games on but also great for developers).
I agree that it represents good value for what it provides, but I can't call it cheap I'm afraid :) I'm just a hobbyist, and for the price of that cart, I could buy (for example) a cheap oscilloscope, five or more AV famicoms in good condition, or a bunch of original games :)
ninja_kun
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Re: simple dev cart for Famicom?

Post by ninja_kun »

I just put a bid in on a RAM adapter, and thinking to buy the FDSStick here: http://www.tototek.com/store/index.php? ... cts_id=196

It talks about this mod chip potentially being required though: http://www.tototek.com/store/index.php? ... cts_id=207

Will I need this mod if I plug the RAM adapter into an original RF or AV Famicom?
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rainwarrior
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Re: simple dev cart for Famicom?

Post by rainwarrior »

The mod is for the FDS disk drive (to make it possible to write the whole disk).

If you're using the FDSStick as a replacement for the drive (i.e. just FDSStick + Ram Adapter), you don't need to mod your drive.

If you want to use it to make copies of disks (FDSStick + disk drive), you might need the mod. See: FamicomWorld article.
ninja_kun
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Re: simple dev cart for Famicom?

Post by ninja_kun »

Got it, thanks!

I found a nice simple explanation of the FDSStick here for anyone else looking for a summary of what it does and how it works: https://www.youtube.com/watch?v=CyDLHbt67FU
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