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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<Foone>
I don't get it
<cr1901_modern>
I think you were making a Baker's Dozen joke?
<Foone>
I mean the "find 1 exploit and get 255 free" part
<Foone>
is it a joke about bytes? byting into bread?
<whitequark>
integer underflow joke?
<whitequark>
oh
<cr1901_modern>
I interpreted it as "one exploit was hiding about 255 more in plain view" and something about bytes
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<ZrX-NoMs>
Same track before and after processing.
<cr1901_modern>
How should I interpret the lines then?
<ZrX-NoMs>
Encoded MFM format as it's on the floppy.
<whitequark>
ZrX-NoMs: whoa
<whitequark>
what's the code?
<ZrX-NoMs>
I started thinking about how the bits are behaving out when the bands start to smear like that, trying to find a pattern and then to reverse it.
<ZrX-NoMs>
Taking three consecutive flux times, if they're certain way out of the norm, take and substract the error from the middle flux value, split it and add the halves to the other flux values.
<whitequark>
have you tried demodulating and parsing the sectors?
<ZrX-NoMs>
The disk that sample was from is now correctly decoded to disk imagefile.
<whitequark>
nice
<ZrX-NoMs>
Was from some PC 5.25 HD floppy from 1991.
<cr1901_modern>
Why are there gaps where the signal is at "constant 1"?
<ZrX-NoMs>
That image show three full sectors and the beginning of the fourth sector.
<cr1901_modern>
I would expect there to be transitions even between sectors :P
<ZrX-NoMs>
Where you see two lines are the gaps. One line is where you start looking for a header or data sync.
<Lord_Nightmare>
ZrX-NoMs: are you testing a new data separator logic?
<Lord_Nightmare>
I saw some discussion of the commodore amiga data separator circuit patent recently, which i believe can be emulated entirely digitally
<Lord_Nightmare>
whitequark also designed that cool PLL that was mentioned on twitter a while back (and i think has since been updated in the glasgow source tree?)
<whitequark>
it was actually azonenberg who designed it