Dual MSX Audio - how does it work in real HW?

By sdsnatcher73

Champion (496)

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10-08-2019, 22:20

So I found some demo/music disks that support 2 msx audio modules. In openMSX there are an ‘MSX AUDIO’ and an ‘MSX AUDIO 2’ extensions and when adding them the disks recognize both. I see in the xml the ‘MSX AUDIO 2’ that it uses a different I/O port.

The demos predate openMSX so probably this was possible with real HW, but did it require modifications on the board?

I have a Toshiba HX-MU900 (upgraded to MSX-AUDIO, with 256k sample RAM and BIOS) and a stock Philips Music Module. I’d love to try this out on real HW...

What I get from GR8NET manual is that MSX audio bios will detect C0/C1 in use by other Y8950 and set it’s Y8950 to C2/C3. Probably if at least 1 Y8950 has MSX-AUDIO BIOS this should work (so I could try it with my 2 modules)

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By alexito

Hero (522)

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11-08-2019, 00:18

Well, good luck with that and let us know because I never get Dual Music Audio from 2 Philips NMS-1205. I own one NMS-1205 (Bios v1.3) and the other NMS-1205 doesn't have BIOS at all. what I did was connecting my GR8NET in Cartridge Slot 1 and the NMS-1205 without BIOS in cartridge Slot 2 so GR8NET will show us it's using MSX IO Ports C2/C3.
Other great Music Audio Device is FS-CA1 from Panasonic because it behave exactly like GR8NET just not showing the MSX IO Ports in use. If you want to try other Software I invite you to try my games mod:

Space Invader Collection with Dual Y8950 ADPCM support
Operation Wolf Enhanced with Dual Y8950 ADPCM support
Pleasure Hearts with Dual Y8950 ADPCM support

Just google it over here at MRC Forums.

By Grauw

Ascended (8317)

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11-08-2019, 01:46

For 2x MSX-AUDIO I think people make a hardware mod to change the I/O address of their Philips NMS-1205 or Toshiba HX-MU900. They don’t have the MSX-AUDIO BIOS so I don’t think they have a software switch to change the I/O base port. The Panasonic FS-CA1 is the only real MSX-AUDIO device, however it’s quite rare.

By quiebitiel

Supporter (4)

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11-08-2019, 04:36

I am interested in this matter.

If MSX-AUDIO BIOS is installed in NMS-1205 or HX-MU900 with music module expander, will IO ports change automatically when using two of them?

In addition. I have an HX-MU900 with music module expander. How can I change the HW to install MSX-AUDIO BIOS 1.3b?

The following was written on FRS's web site.

Quote:

This new version is bigger now requires a 64KB ROM.The Philips Music-Module upgrade board already supports this.It's just a matter of installing a 27C512 EPROM and jumping the board accordingly.For the Toshiba Music-Module, a small mod of the upgrade will be required.

By sdsnatcher73

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11-08-2019, 08:07

Okay will test it when I have access again to my HW. I wonder if Eugeny did anything special for GR8NET or if it is actually MSX-AUDIO BIOS handling the I/O port change. I've seen video's of a guy using two FS-CA1's in a turbo R (not a pretty sight with those 2 carts imho), so who knows... BTW my HX-MU900 has bios 1.2...

It of course depends on the possibility of the hardware to actually switch the I/O ports (and the Philips and Toshiba modules may not have been designed to allow this.

By raymond

Champion (380)

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11-08-2019, 08:41

You can change you Philips Music Module when following this document (it is in Dutch though): Modify Music Module

By sdsnatcher73

Champion (496)

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11-08-2019, 12:22

Okay, I wonder if that modification also works if the module were upgraded to MSX-Audio (possibly with a slightly modified BIOS).

By alexito

Hero (522)

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11-08-2019, 21:29

I have some pictures of my already sold NMS-1205 with 256KB ADPCM RAM and MSX I/O (C0-C1/C2-C3) switch:

https://drive.google.com/open?id=1oJ_qIaqenFkXSh8mwNhWNLBQnd...
https://drive.google.com/open?id=1yAShKVmRgr-UoERQEw9LRmka5c...
https://drive.google.com/open?id=1lOmcLYnvfLg_q0UM3PfyzmG9ew...

as you see in the pictures that Music Module doesn't hold a BIOS maybe because the Switch really I don't know.
Let us know how was your mod because I still have 2 more NMS-1205 waiting for a mod also.

PS: I forgot to take pictures from the solder side of the NMS-1205 PCB, sorry.

By Grauw

Ascended (8317)

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11-08-2019, 22:11

quiebitiel wrote:

If MSX-AUDIO BIOS is installed in NMS-1205 or HX-MU900 with music module expander, will IO ports change automatically when using two of them?

No. Otherwise there would be no reason for people to make hardware modifications to change the base address, because it could be done through software regardless if the MSX-AUDIO BIOS is present or not.

The Panasonic FS-CA1 base address switch is done through a memory-mapped register at 7FFFh, which is not supported by the Philips NMS-1205 or Toshiba HX-MU900 according to openMSX sources.