ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs:
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<whitequark> btw
<whitequark> cr1901_modern: Lord_Nightmare: talked to the SEM lab i had in mind
<whitequark> the lab thinks they can read implant ROM with SEM
<whitequark> so i'll try that before etching
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<cr1901_modern> whitequark: excellent, looking forward to it
<whitequark> it's not going to be *super* cheap
<whitequark> about $25 per sample
<whitequark> i mean, if i was in the US they'd probably charge me $800 just to talk to them
<whitequark> i also asked about delayering and it looks like i can delayer it right at their office (? wherever the fuck the SEM is, i dunno if it's an office or not)
<cr1901_modern> Still 1/6th the price of dr. decap ($150), which back in 2011 was about 1/10 of the price of a commercial lab to do the same (~$1500). And dr. decap used ioactive's equipment during off hours AIUI
<whitequark> so that reduces the cost radically
<cr1901_modern> $25 is still the cheapest I've seen yet.
<whitequark> anyway, once i have the images i'd appreciate if people chipped in
<whitequark> hm, i actually wonder if maybe NMOS automated tracing would work better on SEM images
<whitequark> Sarayan?
<cr1901_modern> sure that's fair, set up a payp- oh...
<cr1901_modern> well, we'll work out the logistics of that
<whitequark> because if I give them like a shitton of very similar samples at once i'm pretty sure it'd be even cheaper
<whitequark> cr1901_modern: hahahahaha
<whitequark> paypal locked me out completely a few days ago
<whitequark> for not being compliant with some tax bullshit
<cr1901_modern> great... lmao
<whitequark> they want me to fill in a form that literally is impossible to submit
<whitequark> i gave them all my personal details that i emphatically did NOT want to give to anyone, fine
<whitequark> but they wouldn't even TAKE them
<cr1901_modern> I had to give my bank my phone # recently... I was not too happy about that
<whitequark> my bank obviously has my phone # for 2FA on credit card transactions
<whitequark> i actually really hate that
<whitequark> but their tiny 2FA devices are even more prone to breakage or being lost
<cr1901_modern> Yea, but I don't have a CC; they wanted it just so I could log in to query balance
<cr1901_modern> right...
<whitequark> in RU I don't have a CC either
<whitequark> they tried really hard to give me one, I had to swear at their operator because they just wouldn't fucking stop calling, even after directly requesting them to stop
<whitequark> still the banks don't want any liability on debit, so VBV it is
<cr1901_modern> My bank limits the CC spam to paper mail
<cr1901_modern> that I summarily throw away each month, but of course my eyes have to read it
<whitequark> i have no idea if they send me mail because i haven't updated my address with them in like a decade
<whitequark> well not a decade
<cr1901_modern> b/c "what if they send me something important"
<whitequark> five years?
<whitequark> i'm not even sure *where* do they send it
<whitequark> not my problem lol
<cr1901_modern> Anyways, I guess someone can send you a BTC transaction, and then they accept donations to their Paypal to offset the cost
<whitequark> i actually use roommate's paypal for this recently
<whitequark> though btc would probably be more useful in some ways
<cr1901_modern> Ahhh okay, that works too
<cr1901_modern> I don't the cost breakdown, but when the SNES DSP-1 was dumped, it cost I think about $2500? to decap and read out the ROM contents. It was a 4-digit number. Doing it for $25 ~8 years later is quite a difference :D.
<cr1901_modern> Actually wait... it might've been multiple die revisions that were all dumped that drove up the cost
<whitequark> that place wants to bill me in 2.5 hour increments i think?
<whitequark> so more like $125 per 5 samples
<whitequark> they sound flexible, we'll see
<cr1901_modern> I wonder how the MAME "crowdfund" for ROM dumping from images is going
<whitequark> from what i've heard i definitely do not want to be involved with anyone from MAME
<cr1901_modern> I mean I only know of one specific drama (when someone decided to make public who dr. decap really was). Everything else I've heard I filed under "emulation is srs bsns and I want recognition by the general public for doing something incredibly esoteric and niche"
<whitequark> yeah that's not encouraging
<cr1901_modern> Indeed. But I _like_ the idea in principle... get ppl who are bored to identify 1s and 0s :P. It's like a game of Picross/Sudoku or something. I just wonder if said idea panned out in practice
<Sarayan> wq: errrr, you do not want to be involved with anyone from mame?
<whitequark> Sarayan: every time i hear about MAME it's related to some godawful drama
<whitequark> it's just that
<whitequark> it's not even -good- drama
<Sarayan> good emu drame hasn't happened in ages
<Sarayan> I was a tad surprised because, well, I'm one of the main Mame developers
<whitequark> oh.
<superctr> i see there are a lot of MAMEdev people here
<whitequark> well uh i
<whitequark> i take that back i guess?
<whitequark> alternatively: you should talk about non-drama parts of MAME more to offset the public perception ;p
<superctr> i was involved in MAME drama last year, so I shouldn't say much
<superctr> but generally most MAME drama happens outside of the project itself
<superctr> i.e. dumping union etc
<superctr> Dr Decap would fall under that
<cr1901_modern> I have no idea what dumping union is
<Sarayan> wq: the non-drama parts of mame is f.i. what we do on the chip RE :-)
<whitequark> i mean i don't really care so long as the drama doesn't involve me
<Sarayan> I just don't feel the need to say "mame ! mame ! mame !" every five minutes ;-)
<whitequark> lol fine, that's fair
<cr1901_modern> right, I don't think that'll happen. I haven't been caught up in drama and I've been pretty adjacent to emu drama since 2013.
<superctr> btw, caps0ff got the dr decap inventory years ago and is actively working on those chips, so I think we can say that's behind us at this point anyway
<cr1901_modern> Only drama I got involved in on emu forums was politics :P
* cr1901_modern is careful about who he personally invites here
<cr1901_modern> superctr: So you're a MAME dev as well I take it? That makes 4 I can count offhand in here
<superctr> i'm not a MAMEdev
<superctr> though i have contributed code
<superctr> My affiliation is with vgmrips for now
<cr1901_modern> ahhh
<cr1901_modern> I'm not affiliated w/ anybody really. I've just floated between cliques (for want of a better term) over the years, so I get bits and pieces of what goes on
<cr1901_modern> nukeykt: While it's on my mind... do you know of a way to determine from the chip outputs alone which stage of the pipeline the YM2612 is currently in? I suspect it can be done w/ the chips w/ an external DAC, but ones with an internal DAC are more difficult
<superctr> since channels are output sequentially though the dac (using time division multiplexing) maybe it's possible by counting clock pulses after seeing one of the channels on the dac
<nukeykt> Probably via test pin i think. If you set bit 7 on test register 2c, YM2612/3438 will output signal on stage 23, though you'll need count MCLK as well
<cr1901_modern> Just curious, is this from silicon RE, or was it previously known?
<cr1901_modern> Anyways, I just need a specific reference point- the idea is to test FPGA implementation, but to do that you need to bring the FPGA impl in phase with silicon
<nukeykt> I think Sauraen figured out from reading YM2612 silicon
<cr1901_modern> otherwise your results surely won't match
<cr1901_modern> silicon is the ultimate source of truth, but I think there's merit to doing comparison testing as well :P
<nukeykt> A bit info about YM2413's test data output on D0, D1 pins,
<cr1901_modern> (a failure of comparison testing against say, a Genesis running a YM2612 and an FPGA core in tandem, will show the existence of bugs)
<cr1901_modern> nukeykt: Oh that's interesting... there isn't enough test state to dump the instrument ROM?
<nukeykt> Unfortunately no, i gathered this info from analyzing VRC7 and YM2413B/FHB013 die shots
<cr1901_modern> nukeykt: Just wanted to make sure... wq is looking into a service to get the ROM dumped
<cr1901_modern> And if the test mode can read it out, we clearly should prefer that :P
<cr1901_modern> B/c it saves money :D
<whitequark> i mean
<whitequark> it's a good test target
<whitequark> there are def chips with implant ROMs to dump
<cr1901_modern> Good point.
<cr1901_modern> nukeykt: privmsg when you get the chance (if it works on the web client)
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<cr1901_modern> nukeykt: How can the test data be used on the YM2413? It _looks_ cool and all, but I can't visualize how I'd use the LSBs of "operator 0" (did you mean "instrument 0"?)
<cr1901_modern> "the modulator* of instrument 0"
<superctr> because you can adjust the parameters of operator 0
<superctr> including with one of the preset instruments
<cr1901_modern> But you only have the LSBs
<cr1901_modern> isn't the phase generator 10 bits
<cr1901_modern> and you only get 9 of them
<nukeykt> Phase generator is 19 bits
<superctr> well, LSB matters most if you want to do measurements over just a few samples
<superctr> for example, you can get the envelope rate by checking the measurements of sample n and n+1 and look at the difference
<superctr> you don't need the MSB for that
<cr1901_modern> hmmmm
<cr1901_modern> nukeykt: oh well the sine ROM is delta compressed to 1 quadrant of 256 samples. Multiply by 4 and you get 10 bits. I guess the other 9-bits are after the decimal place in fixed point
<nukeykt> yeah
<cr1901_modern> superctr: Okay I see what you're saying now. The 9 bits of mantissa (or whatever term floating point ppl use) would be enough to get the envelope rate
<cr1901_modern> significand*
<superctr> well, since this is the phase generator, perhaps you can get MUL and DT instead
<superctr> but same applies to the envelope bits if you don't get all of them
<cr1901_modern> Okay, not synth related, but I think a large chunk of ppl will relate:
<cr1901_modern> How many ppl got stuck on the barrel?
* cr1901_modern did... found out the solution by accident
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<Nerionaya> the solution is to use the level select cheat
<fseidel> I got stuck on that goddamn barrel
<fseidel> ended up finding a gameFAQ with the solution
<fseidel> wouldn't have been such a pain if it didn't respond to jumping, giving a sense of false hope
<cr1901_modern> Lord_Nightmare: Did the relevant MAME commit for VRC7 include a link to the Wiki?
<cr1901_modern> I mean I didn't advertise it, so I was wondering who did
<cr1901_modern> Ahhh okay looks like it was rainwarrior who updated the NESdev wiki. I'll have to thank them
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<cr1901_modern> rainwar: This is a stupid question, but... is this you?
<rainwar> yeah it's me
<cr1901_modern> Oh, whoops
<cr1901_modern> >(5:00:41 PM) cr1901_modern: Ahhh okay looks like it was rainwarrior who updated the NESdev wiki. I'll have to thank them
<rainwar> well i'd mostly just wanna thank nukeykt for dumping the patch set ;)
<rainwar> but I was very happy to verify it
<cr1901_modern> I've already thanks nukeykt. I was just happy that there was a link back to the sipr0n wiki for "exposure" :P
<rainwar> hmm, should probably also add a link to the die shot... surprised that was never put on
<cr1901_modern> I keep a photo around w/ the instruments table circled :P
<cr1901_modern> rainwar: Fun fact... I don't use a bouncer either. I just always keep my damn laptop on :P.
<rainwar> I mostly just try not to think of chat rooms as something I need to know everything that happens in. ;P
<rainwar> In some ways it's a relief to have less information to sift through.
<cr1901_modern> I've gotten used to not keeping up w/ all the channels I'm in
<Sarayan> mu50 main romz, cool
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<Sarayan> yeah, everybody uses the name "Xyz", it's so damn hard to distinguish them ;-)
<Xyz_39809> what an asshole
<Sarayan> Xyz? Or Xyz?
<cr1901_modern> Clearly Xyz is the asshole
<Xyz_39809> The latter. That first guy is alright
<Sarayan> Everybody blames Zathr^WXyz anyways
<cr1901_modern> Nerionaya: The level select cheat is more difficult than the barrel of doom ._.
<Nerionaya> as a kid I remember usually doing the sonic 2 cart swap trick; I did it the proper way once and felt like a god
<cr1901_modern> Yea I've never done it the proper way. Always the swap trick
<cr1901_modern> very fortunate that the RAM vars coincided
<Xyz_39809> I just played the game and pressed every button when on the barrel
<cr1901_modern> (which leads credence to the idea that the assembly files defined RAM vars as "foo .equ $ffff00", etc, rather than automatically allocating them