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Sega Mega Play reprogrammable flash cartridge

TulioAdriano said:
Lol this is a wild idea... but it can probably be done, yeah.
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Usually people just laugh at my ideas. 99% of the time i must admit they are non viable solutions no matter how good they sound in theory. Thank you.

If someone do decide to give it a go, it can be made using one whole pcb with connectors in line with the onrs on the mobo so no need for flying wires everywhere. Some themed silkscreening and winner winner chicken dinner 🤣

Sign me up for preoder please..
 
Monstermug said:
Usually people just laugh at my ideas. 99% of the time i must admit they are non viable solutions no matter how good they sound in theory. Thank you.

If someone do decide to give it a go, it can be made using one whole pcb with connectors in line with the onrs on the mobo so no need for flying wires everywhere. Some themed silkscreening and winner winner chicken dinner 🤣

Sign me up for preoder please..
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behind every successful idea is 1000 bad ideas. thats how it works.

also this is very interesting project and i am really excited to see what else comes out of it. id like this to get added to the multiz list
 
TulioAdriano said:
Yep, I'm about to order some shells and labels for myself, hit me on PM and I may be able to include what you need in the same order.

About the multicart, Blio and I had a conversation a few messages above about that. Depending on the kind of solution it can be more or less involved. I personally wanted an automated solution that does not involve modifying the board. But since there's no reset signal from the cartridge, an everdrive-like solution is out of the question. It would either need a board mod, or the cart would have to be dip-switch based.


I'll reach out to my network of 68K gurus, maybe someone is interested?
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Hi, where did you ordered the stickers and shells ? (I found shells in Aliexpress and labels from Mikonos, in a spanish forum)
 
deep said:
Hi, where did you ordered the stickers and shells ? (I found shells in Aliexpress and labels from Mikonos, in a spanish forum)
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Hi Deep, Mikonos makes the labels, and the shells are from AliExpress. There are many vendors for those shells though, so make sure you don't just grab the cheapest one, look for the ones better quality. I'd send you a link but it looks like the ones I bought (shell & boxes) are no longer there.
 
Hammy said:
Did anyone figure out how to enable "attract mode sounds" for the megaplay motherboard yet??
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My tests show that the sounds are being produced by the game, but the BIOS mutes the mixing amp when there are no credits inserted.
I think the best bet would to hope Shane can add that feature when he releases his BIOS. :)
 
Yeah i think it gets "muted" somehow.. in mame the attract sounds always work, but on the board there's no way to get it to work...

Need that real golden axe 2 attract sound... :D
 
Hammy said:
Yeah i think it gets "muted" somehow.. in mame the attract sounds always work, but on the board there's no way to get it to work...

Need that real golden axe 2 attract sound... :D
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I'll study the board a bit and figure out if there's a way to disable it, if you don't mind modifying the board. I get the sense that it has something to do with those 4066 analog switches, because if you crank up the volume really high, you can hear that there's some volume still passing through even when it's "muted".

Probably disabling the switch would make it work but will require some modification or bypass of those chips.
 
Couldnt onr incorporate an osd game select with a cable to triggers the cpu to reset when another game is chosen? Or just let the user mannually reset it? Snes and megadrive multi carts dont have reset in the osd either. Well not that i know off. Manually power cycle isnt that hard.
 
Alright, I finished my analysis.

First a bit of tracing from the audio side:
IMG_3601-Composite-traced.png


The audio gets mixed in and then pass through the TL862 opamp. From there the 74HC4066s do the magic of muting the FM and MD PSG. It seems to keep going into a transistor which I did not race further. On the left side it goes to a via and the rest is too obscure for the picture(s) to identify.

So I did some hands-on visual inspection/beeping. That trace comes from the BIOS Z80 side, and signals the audio switches to close.
Switch-trace.png


And ends up at that ULN2003A, which is an open collector transistor array, pulled up by R49.

Finally then, all you need to do is to ground the trace that connects to the switch control pin for the audio, which I did like this:
IMG_3609.JPEG


Hammy said:
Did anyone figure out how to enable "attract mode sounds" for the megaplay motherboard yet??
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So there you have it. No hard modification needed. Ground that spot (it was the easiest for me, but you could ground pin 12 on either chip as well, or ground it at the source pin 15 on the IC21 as well) and you got attract mode sound while no coins are inserted.

Still, a better solution would be a bios update that does not execute the muting, but that may take time to surface.

Enjoy.
 
Hammy said:
Maybe lifting the resistor will be enough....
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Unfortunately lifting that resistor will not work, because the signal originates on the trace leading to that leg. It was just a good spot to hook up my probe.

You could, however, remove R49 near IC24 would probably achieve the same result. I myself prefer to avoid modifying the board, so the ground hook works well for me.

Monstermug said:
Great work man! So it means a polished multi is in the works?
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You tempt me... 😄

It can be done, yeah but there's a lot of R&D needed to get there. I'm currently deep diving on developing my System 16B game. I could try evolving my flash cart into a multi in the future after the game is done or if I need a break from the game. Thanks for the incentive.
 
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Hammy said:
It's 4 slot anyway, and there's 12 games available... it's not worth a mulit!
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Good point but then again irem M72 got a multi and 4 out of the 8 games was also available on M84 and other hardware. Hopefully a multi would get some originals out from behind the woodwork. But 1:3 is still less than 1:4. Point taken. 8)
 
Monstermug said:
Good point but then again irem M72 got a multi and 4 out of the 8 games was also available on M84 and other hardware. Hopefully a multi would get some originals out from behind the woodwork. But 1:3 is still less than 1:4. Point taken. 8)
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Yeah if I were to do something like that I'd try going fancy and populating all 4 slots each with a game, so one could switch between 4 without needing to reset the system. It would look like a crazy Frankenstein, but then again which multi doesn't? (Well some of them don't, lol).
 
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