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: https://freenode.irclog.whitequark.org/~h~yamahasynths
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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
Stilett0 is now known as Stilett0-away
<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
<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>
>(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