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
<andlabs>
how does it differ from the one in the PS1?
<cr1901_modern>
andlabs: The PS1 embeds the string "SCEA" somehow into the spiral. I don't understand the details, l_oliveira does tho.
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<KillaMaaki2>
Can I ask a question about the key fraction register on YM2151? I can see that according to the datasheet it covers a range of 0 - 100 cents. Is this only "upwards" so to speak? So that 0 is +0 cents, and 63 would be ~+98.5 cents, and if I wanted to pitch bend "down" I would instead need to set the keycode to 1 semitone lower and pitch up from there? Is that right?
<fseidel>
yes, that's correct
<fseidel>
it's effectively just fraction bits for KC
<KillaMaaki2>
Got it. Thanks!
<KillaMaaki2>
Finally got a GCC toolchain up and running for my little project and working on YM controlling logic :)
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<KillaMaaki2>
OOF accidentally got my logic for determining a register address given channel + op numbers backwards so instead of programming ops 1-4 of channel 1 I programmed every op 1 of channels 1-4 and left the other ops at whatever reset values they take. That was a very harsh and loud noise that came out of that thing just now hahaha.
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<cr1901_modern>
KillaMaaki2: Whatcha working on?
<KillaMaaki2>
Working on a sort of custom FPGA retro game console :)
<cr1901_modern>
I think it's a bug that's documented as a feature
<ZirconiumX>
cr1901_modern: as for the PS1 wobble; because Sony had full access to the disc drive, they could detect sideways motion in the track, and so put in the region encoding within this sideways motion that standard CD readers would ignore
<ZirconiumX>
So if you try to copy a PS1 disc with a normal CD burner, it won't encode the wobble, and thus get rejected by the BIOS.
<ZirconiumX>
Naturally this did not stand up to the test of time.
<cr1901_modern>
I guess my question is: how does the wobble encode the data... Foone has a thread on this (Foone, do you have a f***ing thread for everything?!) https://twitter.com/Foone/status/974277587764523010, which makes it sound like the error signal feedback encodes the value.
<cr1901_modern>
Presumably this must mean the signal transitions encode the data, because that's the only way I could visualize a continuously varying sinusoidal error signal encoding 0s and 1s.
<KillaMaaki2>
OK another question: I'm reading this datasheet, looking at the values for note it goes 0 = C#, 1 = D, 2 = D#... and then it seems to skip to *4* for E? In fact it seems to skip one every three notes? Am I reading that right? It seems to sound right but... I just have no idea why it would be like that.
<nukeykt>
cr1901_modern: i think damp is a feature to start attack phase at max attenuation, it is done because envelope resolution resolution is only 7 bit (compared to OPL's 9 and OPM's 10)