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View topic - Buying YM-2413 FM chips from Yahama

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Buying YM-2413 FM chips from Yahama
Post Posted: Wed Jun 29, 2005 5:06 pm
BillyJR tells me he is building a Megadrive flash cartridge that embed a YM-2413 and allows to play SMS games on Megadrive with FM music.

Quote
> you can still buy in Japan Yamaha
> buy 200 chip is 2 USD each.. so total 400 USD
[...]
> also in China have a lot second hand Yamaha chip..but I want to use new one

Interesting. More info later (he's off to sleep).
Mass-modding Master System to add FM ?
I'll try to obtain a few chips for testing, if anyone want to tackle the thing. (http://www.smspower.org/dev/docs/smsopll.zip)
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Post Posted: Wed Jun 29, 2005 9:41 pm
Bock wrote

Interesting. More info later (he's off to sleep).
Mass-modding Master System to add FM ?
I'll try to obtain a few chips for testing, if anyone want to tackle the thing. (http://www.smspower.org/dev/docs/smsopll.zip)


Maybe BillyJR is right, the 'YM2413B' part is still present in Yamaha's current product lineup:

http://www.yamaha.co.jp/product/lsi/prod/sgl/index.html

In fact here's somebody's schematic for it detailing the amplifier section, just for reference: (looks like it hooks up to a PIC micro)

http://feedback.mech.fukui-u.ac.jp/ttt/enjoy/sound/cc_fm.pdf

However the only available package type is SOP, which can be harder to work with than DIP. I'm also wondering if the instrument ROM is the same, because the newer clone parts (presumably based off the YM2413B) are known to sound quite different compared to an original YM2413.

Purchasing anything directly from Yamaha is a bad idea because they of course only want to sell in bulk. I think this had been discussed in the old forums before.

Finding an electronic component retailer in Japan would be much better, as these types of places usually have much smaller minimum orders (like 10 to 100 chips). You are paying more per chip, but aren't forced to purchase thousands of them at a time.

If you can get a hold of these I'd be interested in buying a few. As nice as Leonard's circuit is, I think it could be simplified just a bit (to get that RAM out of the way :)
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Post Posted: Tue Jul 12, 2005 4:00 am
Charles MacDonald wrote

If you can get a hold of these I'd be interested in buying a few. As nice as Leonard's circuit is, I think it could be simplified just a bit (to get that RAM out of the way :)


But I used the ram just to save the hassle of wiring a latch (2 TTLS).
Originally I was going to use a 74LS174 and half 74LS244 for the read back register .... And RAM chips are so easy to get from scrap ... I see no evil in taking a 32KB ram from a dead 486 motherboard and using only a byte of it. Way better than just trash it don't you agree ? ;)

LSO

P.S.: We can exchange the ram for a 74LS670. What you think ? It's a nibble register with addressable inputs and outputs. Properly wired it can act as a 32 bit (4 nibbles) ram. But to do that I think we will have to add 2 OR ports to sum the /detlatch signal with both /RD and /WR ... Any sugestions ?
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Post Posted: Sun Jul 17, 2005 12:05 am
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register .... And RAM chips are so easy to get from scrap ... I see no evil in taking a 32KB ram from a dead 486 motherboard and using only a byte of it. Way better than just trash it don't you agree ? ;)


I agree, if you've got the parts available it's best to use them. :)

Quote
P.S.: We can exchange the ram for a 74LS670. What you think ? It's a nibble register with addressable inputs and outputs. Properly wired it can act as a 32 bit (4 nibbles) ram. But to do that I think we will have to add 2 OR ports to sum the /detlatch signal with both /RD and /WR ... Any sugestions ?


After looking at the Mark-III FM unit schematic, I think you could replace the RAM with a 74HC74 and implement most (all?) of the logic in a GAL22V10 or similar PLD. All that's left would be the sound amplification part of the circuit and the 4066-based switches.
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