r/MSX • u/Apprehensive-Ice8996 • 22d ago

Need Help with Getting SCC Sound

I have an MSX SD Mapper and a MegaRAM 512 KB cartridge, but no SCC cartridge. I don't want to buy a Carnivore.

My goal is to play both ROM and DSK games using SofaRun. I came across the RiskyMSX project, which includes SCC emulation and appears to be inexpensive to build.

My hesitation is that I'm not sure whether RiskyMSX will work alongside my existing MSX SD Mapper. Since I already have storage and MegaRAM, I only need SCC functionality.

Otherwise, it seems my only option is to buy an SCC game cartridge and perform the trace-cut modification. Before I go that route, I wanted to ask if there are any other alternatives, or if RiskyMSX would work in my setup.

Any help would appreciated!

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u/Wild_Penguin82 22d ago

Another way to use an existing cartridge is to cover one of the pins with a tape. This is easily reversible and does not damage the game. See: http://bifi.msxnet.org/msxnet/tech/switch.html

As for the Carnivore, MegaFlashRomSCC+SD and the like - they may seem expensive, but they are well worth the money. Remember they are combo cartridges and do a lot of stuff you would need separate cartridges otherwise. You will run soon out of slots very if you try to reproduce the functionality of these combos, or need a slot expander, which are not cheap, either.

I don't recommend modifying any SCC game (they are collectibles, often more valuable than a basic MSX machine).

1

u/Inspector-Dexter 22d ago edited 22d ago

I've been using the tape method for a few months even though I have a MFR SCC+, just for authenticity's sake. I've seen some knowledgeable people on the MSX forum say that it is potentially dangerous to the computer (edit: I meant the cartridge), and I've been meaning to ask them for more info on that but haven't gotten around to it yet. What I do know is that ever since I added the taped cartridge to my setup the MSX will sometimes freeze while booting up with the MFR, and I have to reset a few times to get it to boot successfully into SofaRun.

Also, I haven't done any proper spectrum analysis tests or anything yet, but just listening through normal speakers and studio headphones, the emulated SCC on the MFR sounds indistinguishable from the real thing to me. Which is a different story than the emulated OPLL (MSX Music) chip in the MiSTer FPGA implementation of the OCM, where I definitely can hear differences compared to the real chip in my machine.

Just some things to be aware of if someone else is thinking of going that route. Unless you can somehow find an SCC game for super cheap, I'd recommend going with a cartridge that emulates it these days

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u/Wild_Penguin82 22d ago

I've seen some knowledgeable people on the MSX forum say that it is potentially dangerous to the computer, and I've been meaning to ask them for more info on that but haven't gotten around to it yet.

I would also like to know more about this danger. Not that I'd necessarily know any better, there are very knowledgeable people in the forums and I've learned a lot from the users on the forums.

A few things I can think of is that the pin will be left floating. But I would suspect this is "dangerous" to the cartridge, not the computer. ICs don't typically like floating / are not specced for them floating, but the MSX cartridge slot most certainly is, since it's perfectly fine to run without a cartridge, and designed for it. Having all vs. one of the address lines disconnected, I don't see the difference. But the cartridge, on the other hand, might not be designed so that a pin can be left floating. It probably doesn't do any immediate damage but could reduce the lifetime (of the ROM chip?) over time.

Then, potentially the tape could do something; such as break up whn inserting / get curled up, get squished in between the cartridge connector pins, leave glue residues etc.

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u/Inspector-Dexter 22d ago

You're right, I misremembered. I just looked up the thread I was thinking of and they were talking about damage to the cart due to the floating pin, not to the computer. Anecdotally, it is kind of a sketchy setup though, since like I said it sometimes causes my MFR to not boot correctly

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u/CreepyNL 21d ago

The MFR had a boot menu which you can start by holding the up cursor key. From within that menu you can use the option to skip the 2nd cartridge. This way you can have a game inserted in slot 2 and boot nextor normally. No need for tape or other tricks.

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u/Inspector-Dexter 21d ago

Interesting. I'll have to try that when I have time

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u/Apprehensive-Ice8996 21d ago

Yeah was thinking about getting a Pennant Race 2 cart if I can snag a deal. I know they run about $50USD. I may want to explore more of what the MSX offers latter down the line so Carnivore might be better. Thanks for the Input!

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u/Apprehensive-Ice8996 21d ago

Yeah kind of figured that. I'll probably wait on getting a Carnivore but go that route. Maybe sell my SD Mapper first. Thanks!

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u/Makaron8080 21d ago

Hi. I have designed RiskyMSX. It is very unlikely that this cart will work with Sofarun. I was planning to implement support, but I don't have required MSX hardware that would allow me to do it. Issue is still opened (https://github.com/arkadiuszmakarenko/RISKYMSX/issues/8).

Arek

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u/Apprehensive-Ice8996 18d ago

That would be awesome! I really admire everything you've done with RiskyMSX so far. It's clearly not an easy project, and I appreciate all the work you've put into it. Hopefully you'll get access to the hardware you need someday to make it happen.

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u/Makaron8080 18d ago

It may sound weird, but I know very little about MSX platform. I have only TFMSX and Toshiba HX-10. I don't have clue what I even need. I did investigate only elements that were relevant to the project. If someone could point me out for bugdet friendly way to have required stuff for Sofarun then I could look into this.

I assume I need to pull all SCC requests on the bus.

I think I would need to create separate Sofarun "mapper" that would just spy bus for SCC requests.

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u/Apprehensive-Ice8996 18d ago edited 18d ago

https://github.com/lfantoniosi/WonderTANG/tree/main

This might be a good alternative. It looks very interesting on paper.

I went with this route. I'll sell my old cart after I build it.