One chip MSX improvement project

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By juliano.oliveira.9421450

Supporter (3)

juliano.oliveira.9421450's picture

17-03-2013, 01:30

when running in the execrom-1 is not the scc ... any switch or we adapt it which slot in the scc de1;
thanks for modification in de1 greatly facilitates loading rom Smile

By caro

Champion (512)

caro's picture

17-03-2013, 19:44

juliano.oliveira.9421450 wrote:

when running in the execrom-1 is not the scc ... any switch or we adapt it which slot in the scc de1;

You can connect the SCC+ in slot 2, set the switch Sw(5), Sw(4) to "10" (Sw(5) - up; Sw(4) - down).

By x-nen Aivalahostia

Paragon (1473)

x-nen Aivalahostia's picture

18-03-2013, 12:22

@caro: Thanks a lot, for your greatest work.
Is possible add the new faetures of Nextor on DE1? http://www.konamiman.com/msx/msx-e.html#nextor

Thanks a lot!

By Ace

Resident (53)

Ace's picture

20-03-2013, 23:40

Hey all, new member here, but not new to the MSX (software emulation introduced me to this awesome line of computers). I just bought a DE0 board to put together a 1ChipMSX clone, and hats off to Caro for having made this thing. Nice work. Cool

However, I've already run into several issues:

-Audio output is EXTREMELY quiet unless the only thing I have on the audio output is a 100nF capacitor to Ground.
-Metal Gear has an annoying high-pitched noise in some of the notes (appears to be around the 13KHz mark going by a spectrum analysis) and falls victim to the missing noise bug mentioned earlier in the thread.
-The SCC chip is much too loud (also noticed there's no individual volume control for each of the audio chips like on the real 1ChipMSX).
-Noise channel seems a bit off.

Think you can fix these issues? If needed, I can provide audio samples from my DE0 (I don't have a real MSX to provide audio samples from, unfortunately).

Also, how do you get Composite and S-Video output out of this thing? I've tried with a few VGA to whatever adapters and the best I got was a grayscale Composite image.

By luppie

Paladin (864)

luppie's picture

21-03-2013, 07:23

Ace, you can check the schematics on http://msx.cat/blog/aivalahostia/hardware/diy/1xip-casola-pbc
This is the schematic from Caro, but with a Scart connector added.

By Ace

Resident (53)

Ace's picture

21-03-2013, 16:48

Thanks for that. I'm gonna try out the audio circuit there, but having a SCART output is not really an option. I'm in Canada, where SCART didn't take off. None of my TVs have SCART inputs, but I do have a Commodore 1084S which uses a DB9 for its RGB input as well as an RGB to Component converter I built myself which uses the same plug with the same pinout (I would rather use the latter as the converter is hooked up to my 27" CRT TV). I was asking about Composite and S-Video as I would like to record some gameplay footage from the DE0 but with the ability to record in S-Video and play using some other video signal.

By Ace

Resident (53)

Ace's picture

24-03-2013, 19:08

Looks like I can't edit my posts on this forum, but I have a question for those who own a real MSX and a copy of Salamander. Could you put some non-conductive material over the sound pin of the cartridge and record the resulting PSG-only output? I only have blueMSX and some YouTube videos of the game recorded on different MSX computers to go by (but the MSX recordings don't have just PSG), and I managed to get a sample of just the PSG from Salamander on my DE0, and comparing the samples, not only is the PSG noticeably off, but there's also missing percussion. Here's the audio sample I took from my DE0 of Salamander's PSG output using Power of Anger (this is in FLAC format): http://www.mediafire.com/?00edxpyyjugf59i

First off, what is that obnoxious noise I hear at times? Is that caused by the use of PWM for audio generation or does the DE1 do the same thing with its on-board DAC? Second, are the square waves supposed to be that short? blueMSX suggests otherwise, but which one is correct compared to a real AY-3-8910 and YM2149?

If the noise turns out to be a PWM problem, would there be some way to hook up a real AY-3-8910 or YM2149 to the DE0 and completely omit the FPGA AY-3-8910/YM2149?

By vanfanel

Champion (446)

vanfanel's picture

24-03-2013, 20:16

@ACE: I can't help you as I don't have (or want) old MSX stuff, all I have now is the Altera DE1.
However, I can give you a hint about missing PSG percussions: they were NOT lost before.
They got lost when CARO added a fix for Eggerland in an old release.
Look at my posts here:

Posts about lost percussions

I could manually disable the fix, thus getting percussions back (you can also notice the lost percussions in Penguin Adventure's bad santa shop), but then I would get the high-pitch tones in Eggerland, too.
I hope these things get fixed in time, when people realizes how important FPGA replication is and stops losing time with aging hardware.

By Ace

Resident (53)

Ace's picture

24-03-2013, 20:41

I would much prefer a real MSX, particularly for audio recording as I do a lot of that, but at the prices I see MSX2s, MSX2+es and especially MSX Turbo-Rs, it was more financially sound for me to buy a DE0 and make a 1ChipMSX clone out of that instead.

I'm well aware about the missing percussion as I read through this thread quite a bit in the month leading up to my purchase of the DE0, but the inaccuracies with the AY-3-8910/YM2149 appear to be more pronounced than just missing percussion. Which makes me wonder if it's possible to completely disable the AY-3-8910/YM2149 and hook up a real one to the DE0. If it would be feasible to at least do that, I'd go ahead and do it.

By vanfanel

Champion (446)

vanfanel's picture

25-03-2013, 10:09

@Ace: any dependency on old hardware leaves us in the hands of speculators and most people would be unable to attach a physical AY-3-8910/YM2149 to the board anyway as it would require good soldering skills.
In the general interest of the MSX standard, we should go full FPGA now. Look at the Amiga scene!

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