VOGONS

Search

Common searches

Search results

Display options

Display options

Re: Roland SCC-1 - MIDI garbled?

Posted on 2017-07-25, 15:47

in DOS
I'm think there are some damage in traces between PCM chip and sample ROMs. One day i tried to desolder ROM chip from SC-55mkII to dump it. And I broke some chip legs and traces on PCB. It sounded similar to attatched sample. Fortunately i've fixed it.

Re: YMF262 design flaw

Posted on 2017-07-14, 22:28

That is very exciting info, I am so amazed/stunned by this. I'll definitely try these after I've tested the attack rate thing. I've been thinking if this is the correct way to test it: -initialize all registers so chip produces dead flat zero value silence -configure one channel so that only one …

Re: YMF262 design flaw

Posted on 2017-07-14, 16:52

Figured out some of the LSI test(0x01) register functions. Note that i haven't tested them on hardware. This list can be incomplete or incorrect. bank 0 0 - Disable EG output 1 - Disable LFO timer(possibly also timer) / Set Noise generator's next bit value to 1 2 - Reset phase generator counter 3 - …

Re: YMF262 design flaw

Posted on 2017-07-13, 13:36

Hi nukeykt. Is this a significant bug fix that can be heard on most games like your samples above? The technical stuff is way over my knowledge, is there a significant difference? I think this bug never appears in any game. To trig it should change attack rate to 15 after keyon. I don't know any …

Re: YMF262 design flaw

Posted on 2017-07-13, 01:24

Hi! Noticed Lord Nightmare mentioned me so I decided to make an account. You're doing good and fascinating work that complements my own/LN's! :). Might as well give an update while I'm here: I did a blog post as a tutorial about REing NMOS chips such as the YM2151 and friends back in October. A …

Re: YMF262 design flaw

Posted on 2017-07-13, 00:50

Wow, that's some pretty deep stuff you've been working on. So how come the MAME polynomial matches the output of real chip then? Is it just that the operator that was under examination used every N:th bit of the noise generator, so MAME polynomial matches every N:th bit of the original noisegen? I …

Re: YMF262 design flaw

Posted on 2017-07-12, 18:52

I'll put it on my todo list but I can't make any estimate when that will happen. Meanwhile, can you provide some information about this die shot reverse engineering, I'd be happy to read and maybe comment on something, although my experience is only limited to figuring out OPL2 KSL lookup table …

YMF262 design flaw

Posted on 2017-07-12, 17:53

Hi Recently i was working on next version of Nuked OPL3 emulator based on YMF262 die shot analysis. I think i found an error in chip design. YMF262 is specially treating attack rate 15: it just sets envelope to max value. Logic gates responding for this likely has an error. The logic looks like this …

Re: Nuked OPL3 Patch for DOSBox(+Windows build)

Posted on 2017-06-10, 17:53

The friend in question is me. I am doing this in 86Box which is a fork of PCem. It uses (old?) dbopl.cpp, which has a variable that when turned off, makes the code pretend to be an OPL 2 and make the required adjustments. But nukedopl.cpp has no such switch and I'd rather not write my own code to …

Re: Nuked OPL3 Patch for DOSBox(+Windows build)

Posted on 2017-06-10, 17:47

nukeykt, Is this how dosbox does OPL2 with its cores, It just ignores high bank writes when using the opl core? It seems that there is a separate OPL2 emulation in dbopl cores besides the OPL3. DBOPL is a combined OPL2/OPL3 emulator. When OPL3 mode disabled it emulates OPL2, when you enable OPL3 it …

Re: Nuked OPL3 Patch for DOSBox(+Windows build)

Posted on 2017-06-10, 16:27

A programmer friend asks a question about how nukedOPL enabled OPL2 modes: "How do I set NukedOPL into OPL2 and Dual OPL2 modes?" For OPL2 just ignore high bank writes. There are two ways to emulate Dual OPL2: 1) "True" Dual OPL2: Just run two instances of the Nuked OPL3 for each OPL2. But it would …

Re: Nuked OPL3 Patch for DOSBox(+Windows build)

Posted on 2017-06-09, 10:45

@nukeykt Do you have a YM3812 version too of nukedOPL? I ask because SB1.x,SB2.0,SBPro1 are still using the less accurate OPL2 emulation. No. I cancelled it due to 2 reasons: 1) For me OPL2 sounds exactly like OPL3. Indeed, Nuked OPL3 sounds closer to OPL2 than any OPL2 emulator. 2) As i mentioned …

Re: For you CQM haters & lovers

Posted on 2017-05-04, 19:51

(all my tests gave bit perfect output, but probably they don't cover all cases). A torture test is not hard to create using AT2. Where it can go wrong is in the 4-Operator mode where more complex wave forms are created. Did you test with the worst possible combinations of feedback and pitch in 4-op …

Re: For you CQM haters & lovers

Posted on 2017-05-04, 19:05

Probably some OPN2 findings will be incorporated into Nuked OPL3. This is interesting, such as what? I thought your OPL3 is bit-perfect and complete? I meant if i'll find them. There are a lot of common things between Yamaha chips. Initially i started with black box testing of YMF276 and wrote …

Re: For you CQM haters & lovers

Posted on 2017-05-04, 17:48

but writing a bit-perfect OPL emulator has lost its appeal as there's just too many of good enough for general use emulators. There is one here on Vogons and it's part of the SVN-ECE fork by Yesterplay80. NukedOPL by the user nukeykt is a bit perfect OPL3 emulation. http://www.vogons.org/viewtopic. …

Page 3 of 6

Go to top of page Go to top of page
Close window
Close window