Modding Cartidges, Diagrams with Stereo & Clock Oscilator ...

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Por sd_snatcher

Prophet (3135)

Imagen del sd_snatcher

06-10-2011, 23:06

@Dhampird

Very, very nice! Specially the SCC and SCC+ oscillator fixes. That will save me a lot of work/testing. It's great to have someone else also creating mods to fix/upgrade MSX classic hardware. Smile

I have some questions and suggestions about some mods though:

1) The SynFox SD interface clockfix seems to be perfect: The CPUCLK signal from the MSX slot goes to the SD-Card, and the new cristal oscillator clock goes to the SCC sound reference input. It would be great if Synfox updated his schematics to include this fix.

2) Please publish a clock fix for the standard Konami SCC cartridge. It will be very similar to the Synfox cartridge. Smile

3) On the MegaFlashROM SCC+ Cartridge, it would be good if Manuel Passos could validate it and check if it will not cause any collateral effects because of the different clock timings

4) On the Snatcher SCC+ cartridge, here's a little suggestion: The SCC+ have two CLOCK inputs for a reason: One is the SND_CLKIN and the other is the CPU_CLKIN. The CPU_CLKIN is used to interface the Z80 with the DRAMs of the cartridge and needs to be connected to the CPUCLK pin of the MSX slot. The other pin is just like the SCC CLKIN pin: used for the sound reference, and should must be connected to the crystal oscillator. It's very similar to the fix you did for the Sinfox SD-Interface. If the mod is applied as it is now, the original SD-Snatcher game will not work on the cartridge anymore, and it will only work with games hacked to run on the memory-mapper instead of using the cartridge's bult-in DRAM.

The problem is: you must discover which pin is the SND_CLKIN and which pin is the CPU_CLKIN. To discover that, proceed as this:

1) A game hacked to run on the memory mapper (either SD-Snatcher, Snatcher or KGCs)

2) Disconnect one of the two ???_CLKIN pins from the crystal oscillator. Leave the pin other connected

3) Run the game and check if still there's sound being produced. Take note of the results.

4) Now invert the test: disconnect that pin from the oscillator and connect that one that was disconnected on the 1st test. Take note of the results

The pin that was able to maintain the sound generation is the SND_CLKIN. The pin that resulted in a silent cartridge is the CPU_CLKIN. Please post the results here so ant0niutti can update the SCC+ pinout on his website. Smile

Good luck and keep up the good work!

Por sd_snatcher

Prophet (3135)

Imagen del sd_snatcher

06-10-2011, 23:35

Just asking, what is the point of the oscillator in a cartridge? Is there some problem with SCC if an MSX in installed with turbo, and this removes that problem?

The vast majority of MSX sound cartridges were designed in the old times without their own sound frequency reference just to save a few dollars on a crystal oscillator. That was a bad design decision, and means that the sound pitch was unnecessary tied to the CPU speed (can you believe that?). When the turbo is enabled the sound pitch goes high, distorting the music.

This is the case of:

- Konami SCC
- Konami SCC+
- Philips Music Module (NMS-1205)
- Toshiba Music Module (HX-MU900)
- Panasonic MSX-Audio (FS-CA1)
- All MSX-Music cartridges (FM-PAC, FM-PAK, FM-Stereo etc)

For the newer designs, it seems that many of them were based on those old designs, and thus inherited this flaw. The only new cartridge exceptions I know that have been designed correctly and include their own crystal oscillator for sound reference are:

- Sunrise's Moonsound (and its clones: ShockWave, Dal Ri Sol)
- Leonardo/MSXpro's OPL3 Cartridge
- Padial's SAN3 sound cartridge

The cristal oscillator fixes that Dhampird is publishing here are meant to fix this sound-pitch problem. It's fully compatible with MSX of any clock speeds. I'm very glad he's doing that, because many people keep asking me to fix it by software on my TurboFix patches, but it can't be fixed that way. It's a hardware issue and needs to be fixed by hardware modding.

New designs should have a look at this thread for reference. Let's hope that with the new MRC website we have a wiki to include all this info on a "Design guidelines for new hardware" page. :)

Por Gradius2

Hero (574)

Imagen del Gradius2

06-10-2011, 23:58

I don't understand that "PSG" begin as pin 49.

Pin 49 is used for Sound Input, not output, nor PSG sound.

There is no PSG sound coming from any pin on the slots.

This mod isn't true stereo, is just separating SCC sound from PSG, so SCC get in one channel, and PSG into another, not stereo at all, I remember I did this in 1987 with Parodius and other MegaROM games back there, it gets weird.

Por sd_snatcher

Prophet (3135)

Imagen del sd_snatcher

07-10-2011, 00:04

BTW, Dhampird, where did you bought the HO-22B crystal oscillator?

Por Gradius2

Hero (574)

Imagen del Gradius2

07-10-2011, 00:07

BTW, Dhampird, where did you bought the HO-22B crystal oscillator?

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=3.579&_sacat=See-All-Categories

Por sd_snatcher

Prophet (3135)

Imagen del sd_snatcher

07-10-2011, 00:18

@Gradius2

Yes, I've had searched on ebay already. Those are common 2-pin crystals, not the type of 4-pin crystal-oscillator Dhampird used here.

The 4-pin crystal is a much more complex device that already outputs its signal at TTL level.

Por Gradius2

Hero (574)

Imagen del Gradius2

07-10-2011, 00:20

I know those 4-pin (used 1 in my Xonar STX), actually is always just 3 pin:

- VCC
- GND
- CLK

Those "2 pins", have all of above.

Those "4 pin" are only a bit more stable.

Por sd_snatcher

Prophet (3135)

Imagen del sd_snatcher

07-10-2011, 00:39

Hummm, wouldn't that mean that like the 2-pin crystal, it would be recommended to use:

1) A pair of 22nF capacitors, for the crystal to boot?
2) For the SCC/SCC+ it would be recommended to pass the signal through a pair of NOT ports (74HC04) to adjust the signal to TTL levels?

Por Dhampird

Hero (585)

Imagen del Dhampird

07-10-2011, 07:59

Hello everyone, first of all I am glad that this post is subject of discussion, because this, is how together we can find better results to make new mods or changes in our machines, or find new ideas. I think that way. I have a special attachment to msx, especially to MSX2 HB-F9S model, that was my first computer. I've been almost last year trying to make modifications in that model with purpose to let HB-F9s works in a high level of compatibility, and it has been possible thanks to much people of this forum that let me know how that msx2 works. I could go forward in the process, and now, I'm closer to finish with MSX2 HB-F9S. I hope i can get this soon. I would like to mention that I am no msx expert in hardware or software, I am learning new things every day thanks to that expert tips and fully guidelines from specific msx.org people. I want to thank all people who have helped me in this process, seriously, thanks.

All that audio "stereo" diagrams are based in a L.Padial job that he built for my Sinfox.

Said that ,I'll try to answer all questions, as far as I can:

To "OeiOeiVogeltje" questions:

-What kind of stereo is this? drums on one side and rest on other side? or what?

-I think this is not a real stereo, it is a pseudo-stereo, this allow ear channel right and left through HI-FI speakers by mix PSG (activating or deactivating switch) and SCC (only, or mixed with PSG). I have a Pioneer VSX HI-FI amplifier, i get signal out from cartidge stereo jack with a stereo cable , and then, this cable goes to a CD input position in the amplifier. I record the audio result from amplifier phone jack with my iRiver iHP-140 mp3 jukebox recorder, the audio .mp3 track result is below, i can tell when you ear it that this audio result is poor if you compare to ear the real sound result from 5 speakers + Subwoofer in Hi-Fi, for me result is outstanding, i get same good result if i ear the audio with my stereo phones Sennheiser HD595, it seems the record i uploaded shows a little background noise, that is not perceptible if i use stereo phones or if i ear from 5 speakers + subwoofer. Anyways here you are the 2 .mp3 file records result if you want take a look:

Snatcher intro, sound get from real Konami Snatcher SCC+ stereo jack & Vampire Killer, sound get from LPE-SANS, (Padial Stereo Sound Card):

www.megaupload.com/?d=TLHO1B6K

To "Dantyr" questions:

-Let us know what results you get when you have some time, will be great know other methods. Feel free to put all info you want to post, images, etc. This is the real reason to post.

To "Wild_Penguin" questions:

-What is the point of the oscillator in a cartridge? Is there some problem with SCC if an MSX in installed with turbo, and this removes that problem?

-Most of msx sound chips, i think all of them, works at 3.58Mhz, that is the standard msx machine CLOCK (CLK) speed, if you install a Turbo Kit upgrade, for example 7Mhz, when you put Turbo ON the 7Mhz CLOCK speed also affect to the sound chips because in this case, talking about cartidges, the 7Mhz CLOCK should go to CLK SLOT, making a sound distorsion if you have a SCC (for example). To avoid it you have to install a 3.58Mhz clock oscilator into the cartidge, this allow that sound chips still working at normal speed (3.58Mhz), then sound distorsion not appear more, meanwhile this allow still use Turbo features if you have on that SLOT the 7Mhz. You can read better explanation of this made by
"sd_snatcher" a few lines below.

To "sd_snatcher":

Hi sd_snatcher! How are you? :), well, like i said before the Sinfox was fixed for L.Padial time ago, i take this installation as an example, then I've done the other cartidges mods. Ok, about:

1) The SynFox SD interface clockfix seems to be perfect: The CPUCLK signal from the MSX slot goes to the SD-Card, and the new cristal oscillator clock goes to the SCC sound reference input. It would be great if Synfox updated his schematics to include this fix.

-Yes, after L.Padial made that mod for me, i followed where CLK tracks goes and it seems works like you exposed, "Retrotechie" in that time warning me that the clock oscilator in Sinfox, should affect only to SCC part, not to the SD, because the Sinfox uses that clock signal (Turbo in this case) for some kind of SD timings. I think the same, the Sinfox is a pretty piece of hardware and with similar mod oscilator for only the SCC, and maybe another 512K flash will make a much better cartridge. Maybe in a future (distant), i still dreaming..., we could see in only one cartidge all msx hardware possible together...i mean, sound card, flash, mmc, megaram, real stereo, etc etc. ( 5 or more FPGA running at same time?) LOL!

2) Please publish a clock fix for the standard Konami SCC cartridge. It will be very similar to the Synfox cartridge.

-Ok, no problem, i have here a F1-Spirit opened, with future purpose to build a megaflash, tomorrow or during this week i´ll upload the diagram and results.

3) On the MegaFlashROM SCC+ Cartridge, it would be good if Manuel Passos could validate it and check if it will not cause any collateral effects because of the different clock timings.

-Yes, that will be great. At first time, i had a lot of problems in that cartidge with SCC-I sound when Turbo was ON, (using SLOT2 at 3.58Mhz, obviously, when Turbo was ON running at 7Mhz or 8Mhz, like you said me time ago about unstable SLOT at 3.58Mhz speed) sometimes i couldnt ear any SCC-I sound channels towards stereo jack, was strange. I asked to M.Pazos about this, he told me that i should try to ask to "Kazuhiro Tsujikawa", this guy built SCC implementation in Megaflashrom (same like 1chip MSX), he reply me and after talk about the problem and try some things first, after i told about the sinfox oscilator, he explained me that idea should enough to fix the problem... and worked ok, now that "dissapearing channels effect" dont happen anymore, same for A1-GT, SCC-I remains stable at Turbo speeds, and the speed increases in-gaming. I sent to M.Pazos the diagrams, maybe should be another better options, who knows. Like you said, at this moment, "validate it and check if it will not cause any collateral effects because of the different clock timings" wil be great ,expert msx users like M.Pazos could try test it more and after could give to buyers the possibility to get: MegaflashromSCC+Turbo Fix & Stereo. I can tell if that new options will be fully tested by them, i´ll shop again the cartidge.

4) On the Snatcher SCC+ cartridge, here's a little suggestion: The SCC+ have two CLOCK inputs for a reason: One is the SND_CLKIN and the other is the CPU_CLKIN...

-Ok, understood. I´ll try along this week if i have some time. I upgraded the cart with 2 more memory IC´s, now recognise 128K, i download SCROM and ROMLOAD but i have to try to load a game, i couldnt, maybe you´re more about how load a .rom with that soft, if you know please let me know a simple example to dont spend much time on it, i need this to begin with tests. Thanks mate for the fully explain.

"Let's hope that with the new MRC website we have a wiki to include all this info on a "Design guidelines for new hardware" page"

-Yes, i think here in msx.org there is a lot of info, the better info, but maybe some new forum sections in a future could mark the difference, i mean, for example:
Hardware/
Section Sound/
Section Video/
Section Turbo/
Section Datasheets/
Section Tested Mods/
...
something like that will avoid a lot of repeat post, i think this also should be difficult to do, this is only an idea.

"BTW, Dhampird, where did you bought the HO-22B crystal oscillator?"

-Good question!... At first time, when Padial install me the clock oscilator for Sinfox he used different oscilator, that was labeled on top like:

ACT1750P
9948
3.579545Mhz

4 PINS (5V, GND, CLK, NC (no conect))

After understand the mod i´ll try to find that component, but i didnt find nothing!, then when i began to mod by my own the other cartidges i asked L.Padial if he could get more of those 3.58Mhz oscilators, then he sell me the new ones ( i know he bought those anywhere, because he told me that he needed to order that oscilators). Then, i´ll try to ask if he can let me know where he bought the news, i´ll try to find the new ones but i found the same oscilators with more speed clock, not 3.58Mhz, when i have news i´ll post about it.

"Hummm, wouldn't that mean that like the 2-pin crystal, it would be recommended to use:
1) A pair of 22nF capacitors, for the crystal to boot?
2) For the SCC/SCC+ it would be recommended to pass the signal through a pair of NOT ports (74HC04) to adjust the signal to TTL levels?"

-I followed the first Sinfox L.Padial oscilator mod for all cartidges, like you said probably i´ll have to try new variations for test purpose. Is a new idea to follow, thanks for that, i´m wondering where find more msx time... i´m still stuck with the Turbo issue that you know and maybe I have to begin to finish it, i´m also on it. Too much hardware things at same time in MSX = Bad Results :P

To "Gradius2":

I don't understand that "PSG" begin as pin 49. Pin 49 is used for Sound Input, not output, nor PSG sound. There is no PSG sound coming from any pin on the slots. This mod isn't true stereo, is just separating SCC sound from PSG, so SCC get in one channel, and PSG into another, not stereo at all, I remember I did this in 1987 with Parodius and other MegaROM games back there, it gets weird.

-In all msx PIN49 (SOUND) goes from cartidge to internal PSG, and from internal PSG to amplifier, then from amplifier to audio out, we can call this OUT (from cartidge to PSG), if you have this common configuration and for example you want to play a PSG game like Vampire Killer you will not get any sound through the stereo jack (like i showed above diagrams), instead, if you get PSG signal (into msx mobo) that travel after internal amplifier and you redirect it to PIN49 in the SLOT cartidge you´re let PSG internally generated goes to cartidge, like IN, this allow the internal msx sound goes to PIN49, and let ear PSG through jack stereo, this way you can ear the PSG music in game like Vampire Killer. Other simple way to explain, is similiar if you get audio signal from msx Audio Out and you inject that signal into SLOT PIN49. I posted above the audio procedure diagram to follow, is the only way that i know.
The mod separate SCC from PSG and also mix PSG+SCC if i´m right, yes, like i told this is not a real stereo, maybe you can call "pseudo stereo", but for me i can ear it in a outstanding way towards Hi-Fi. Anyways, all alternative methods are wellcome.

Here is oscilator picture and datasheet:

img690.imageshack.us/img690/8849/hosonic.jpg

www.megaupload.com/?d=LZMKOK7P

Like i said i´ll try to post soon something about real SCC+ and normal SCC diagram.

Por Dantyr

Resident (51)

Imagen del Dantyr

07-10-2011, 21:57

Hi Dhampird,

I make the modifications on my cartridge today, but I was unable to upload the photos yet, but I will post later when I get home.

The modifications worked flawlessly, now I have SCC+ sound output coming from an RCA jack on the cartridge and PSG sound coming from the sound output on the MSX, it's a perfectly 'pseudo stereo' as you called it. Big smile I also put a switch to change to the original configuration when using the cartridge on another MSX.
The most difficult part was to cut the cartridge to adapt the RCA jack and the switch.

Thanks for your excellent post that helped me so much to solve this problem.

Thanks,
Daniel

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