One chip MSX improvement project

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By vanfanel

Champion (446)

vanfanel's picture

17-05-2013, 10:20

@caro: I've tried the latest version (15/05/2013) and it's still missing PSG noises.
Cou you please adapt ACE's DE0 version to DE1? it uses original D4 PSG implementation.

It's here, including sources:

http://www.mediafire.com/?vyxqa666g37gmzm

By Ace

Resident (53)

Ace's picture

17-05-2013, 17:10

caro wrote:

It is not the bit RGB-signal and the clock frequency of the computer.
In the OCM (all models in the MSX) using a generator with a frequency of 21.477270 MHz. 6 is obtained by dividing the frequency of 3.579545 MHz which is used to operate the module vencode.vhd (RGB to NTSC video encoder).
In DE0 (and DE1) clock frequency is generated from the frequency of 50 MHz.
50.000000 * 3/7 = 21.428571 / 6 = 3.571428 MHz
As a result, NTSC video encoder does not work properly.
To solve this problem, you can use an external oscillator 21.477270 MHz

Well that explains everything. Thanks for telling me about this; I'm gonna remove the 21.47727MHz crystal on a broken NOAC clone and wire it up to the DE0.

Now, three more questions:

-How would I go about using this crystal instead of the 50MHz clock already on the DE0 for generating color for the TV output?
-I'm going to make a custom variant of the 1ChipMSX using my DE0 with two cartridge slots, two controller ports, Composite video, dual Mono audio and RGB. How could I have the Composite output separate from the RGB? As it is right now on the DE0, DE1 and 1ChipMSX, the Composite and S-Video pass through the RGB pins. I would like to have those outputs separate (I don't mind building some R2R ladders for this).
-How can I remove the MSX3 BIOS from the DE0 code and use a standard MSX2+ BIOS in its place?

Also, you never gave me a proper answer for adjusting the volume levels of the SCC's individual channels. Where can this be done in scc_wave.vhd?

By caro

Champion (512)

caro's picture

17-05-2013, 17:06

vanfanel wrote:

@caro: I've tried the latest version (15/05/2013) and it's still missing PSG noises.
Cou you please adapt ACE's DE0 version to DE1? it uses original D4 PSG implementation.

Try the version from 17.05.13 http://caro.su

By vanfanel

Champion (446)

vanfanel's picture

17-05-2013, 18:36

@caro: I have tried version 17.05.13:

-No audio on right speaker. Only left speaker is audible.
-PSG noises still missing.

Are you using ACE's DE0 audio module?

By caro

Champion (512)

caro's picture

17-05-2013, 18:48

vanfanel wrote:

-No audio on right speaker. Only left speaker is audible.

Yes. PSG on left chanel, SCC+OPLL on right chanel.

vanfanel wrote:

-PSG noises still missing.

I do not know, I think now everything is done right.

vanfanel wrote:

Are you using ACE's DE0 audio module?

Yes, with minor fixes.

By vanfanel

Champion (446)

vanfanel's picture

17-05-2013, 19:51

Quote:

Yes. PSG on left chanel, SCC+OPLL on right chanel.

Sorry but I don't understand it. PSG, SCC and OPL are all MONO? I don't think so.
Maybe:

-PSG is on left chanel
-SCC and OPL in both left and righ channels

But even so, it makes no sense to me. PSG is mono but should be heard on both left and right channes I guess.
Caro, can you please make it like a real MSX and let the PSG sound on both left and right channels again?

It used to work like that in old versions.

By caro

Champion (512)

caro's picture

17-05-2013, 20:51

vanfanel wrote:

Caro, can you please make it like a real MSX and let the PSG sound on both left and right channels again?
It used to work like that in old versions.

Posted version with mono output: http://caro.su/msx/ocm_de1.htm

By caro

Champion (512)

caro's picture

17-05-2013, 20:53

Ace wrote:

Also, you never gave me a proper answer for adjusting the volume levels of the SCC's individual channels. Where can this be done in scc_wave.vhd?

Yes.

By Gradius2

Hero (639)

Gradius2's picture

17-05-2013, 21:20

PSG is mono, can also be for left channel only.

SCC is mono too!

The correct would be making a special "mono > pseudo-stereo" HW filter for those both.

By vanfanel

Champion (446)

vanfanel's picture

17-05-2013, 21:40

@caro: ok, I have PSG on both speakers back, thanks for the mono versions!

However, PSG noise is still missing on the DE1 Crying , Can you please remove your fixes? Maybe we can get full PSG noises then. Just leave the original, untouched PSG files.

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