MSX-Music expanded instrument (0x82): what is exactly?

By AxelStone

Prophet (3189)

AxelStone's picture

11-04-2017, 08:50

Good day everyone, I'm reading about MSX-Music programming and I have this doubt: what is exactly expanded instrument? I mean, there are 3 ways to specify instrument to OPLL:

  • Values from 70H to 7FH: hardware instruments, I understand this.
  • Value 82H: expanded instrument? What this mean
  • Value 83H: user defined? I've read that yo define a custom instrument using 6 bytes, but once they are defined, what means this value? How can I set pointer to defined instrument?

Thanks.

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By AxelStone

Prophet (3189)

AxelStone's picture

11-04-2017, 11:36

Ok I've read about 83H and I understand, but still don't understand how to use 82H. Any idea?

By Sylvester

Hero (576)

Sylvester's picture

11-04-2017, 13:26

Did you see: http://map.grauw.nl/resources/datapack/Vol2-3.3FMBIOS.pdf ?

Is says: Specifies the extra voices. Value of 1 byte following (0­-63) is the built­in sound number of ROM. Most significant bit is ignored reading of this sound number.

So I would say it's one of the voices defined in the Voice Data Table on https://www.msx.org/wiki/MSX-Music_programming

By Parn

Paladin (832)

Parn's picture

11-04-2017, 13:44

If I'm not mistaken, 82h is similar to 83h: it activates the user defined instrument, but instead of loading definitions from an user defined location, they are loaded from the Voice Data Table inside the MSX-Music BIOS. This way you have more predefined instruments to choose from, instead of relying only on the 15 internal OPLL instruments. However, for obvious ways you can't use more than one (or the user-defined instrument) at a time.

When choosing internal MSX-Music BIOS instruments, the two most significant bits are ignored. So instrument 20h is the same as 60h, A0h and E0h.

By AxelStone

Prophet (3189)

AxelStone's picture

11-04-2017, 21:43

Thanks people, it seems that.

By AxelStone

Prophet (3189)

AxelStone's picture

12-04-2017, 07:45

Ok here goes another question about these expanded instruments: where I can get a copy of these instruments? Acording to documentation one instrument is defined with 8 bytes, so inside the FM-Bios must be one space where these 64 instruments are defined, Someone knows address inside the BIOS where are stored?

Thanks!

By AxelStone

Prophet (3189)

AxelStone's picture

12-04-2017, 10:23

Ok I got it, they are stored in Tone Data address, 4C00 - 4DFF.