@nataliapc/mcp-openmsx

# MSX-MUSIC REGISTERS ## WRITE ONLY The registers of the MSX-MUSIC system, as found in: FM-Pac, FM-Stereo-Pak, MSX2+ and TurboR computers, are controlled via ports &H7C and &H7D. The control works according to the same principle as with MSX-AUDIO and the PSG. The register is specified in 7C and the data in 7D. Unfortunately, these are Write Only ports, so they cannot be read. ## SOUND SETTINGS The OPLL data (original instrument) is specified in registers 0-7. This data corresponds to the data you can retrieve in the SynthSaurus Sound Editor, so you can easily retrieve a homemade instrument and write those values to registers 0-7. The following is the structure of registers 0-7 (OPLL instr) ``` Reg.nr. Bit: Function: ------------------------------------------------------------ 0,1 0-3 Multi sample waves/harmonic relations 4 Rate key scale 5 Latching/sprouting (1=Latch 0=Latch) 6 Vibration on/off (1=on 0=off) 7 Amplitude modulation (1=on 0=off) 2 0-5 Modulation index 6-7 Level key scale 3 0-2 FM recoil 3-4 Load-bearing and modulated waveform link (FM/AM) 6-7 Level key scale 4,5 0-3 Decay change 4-7 Attack change (swelling) 6,7 0-3 Opening the change control 4-7 Major of Attack/Decay ------------------------------------------------------------ ``` ## INSTRUMENT CONTROL The registers printed below are for the instrument selection/frequency/octave/volume and the so-called Sustain. ``` Reg.nr. Bit: Function: ------------------------------------------------------------ &H10-&H18 0-7 Note frequency LSB (8 bits) &H20-&H28 0 Note frequency MSB (1 bit) 1-3 Octave nr. (0-7, 0=octave 1, 7=octave 8) 4 Key on/off (1=on, 0=off) 5 Sustain (hold, 1=on, 0=off) &H30-&H38 0-3 Volume (0=vol.15, F=vol.0 !) 4-7 Instrument select (0=original, <>0=FM instrument) ------------------------------------------------------------ ``` ## FM INSTRUMENTS The MSX-MUSIC system has 15 pre-programmed instruments that can be used independently of each other. ``` 0 = Original (custom instrument, see SOUND SETTINGS) 1 = Violin 9 = Horn 2 = Guitar A = Synthesizer 3 = Piano B = Harpsichord 4 = Flute C = Vibraphone 5 = Clarinet D = Synthesizer Bass 6 = Oboe E = ElectrPiano2/Acoust. Bass 7 = Trumpet F = ElectrPiano1/ElectrGuitar 8 = Organ ``` ## RHYTHM Register &H0E contains the drum selection, however bit 5 must be written before a drum can be heard. The drums can also be slightly changed, but rather limited and a bit chaotic. Below is a table of the drum values that can be written in register &H0E: ``` bit 0 = HiHat bit 3 = Snare drum/Field drum bit 1 = Cymbal bit 4 = Bass drum bit 2 = TomTom bit 5 = selector (1 = Rhythm, 0 = Instrument) ``` Of course, multiple drums can be controlled simultaneously. The rhythm sound is structured as follows: ``` Drum type: Reg. Bit: Function: ------------------------------------------------------------ Bass drum &H16 0-7 Frequency LSB (8 bits) &H26 0 Frequency MSB (1 bit) 1-3 Octave (0-7) &H36 0-3 Volume Bass drum Snare & &h17 0-7 Frequency LSB (8 bits) HiHat &H27 0 Frequency MSB (1 bit) 1-3 Octave (0-7) &H37 0-3 Volume Snare 4-7 Volume HiHat Cymbal & &H18 0-7 Frequency LSB (8 bits) TomTom &H28 0 Frequency MSB (1 bit) 1-3 Octave (0-7) &H38 0-3 Volume Cymbal 4-7 Volume TomTom ------------------------------------------------------------ ``` ## BASIC REGISTERS The registers of the MSX-MUSIC system are, under BASIC!, maintained from address &HF9C0 to &HF9C0+&H38. The settings of these registers are filled with the following values after the command CALL MUSIC: ``` Reg.nr. Value: ------------------------------------------------------------ Register pair 1: Instruments &H10-&H15 &H56 Drums &H16 &H20 &H17 &H50 &H18 &HC0 Register pair 2: Instruments &H20-&H25 &H00 Drums &H26 &H05 &H27 &H05 &H28 &H01 Register pair 3: Instruments &H30-&H35 &H30 Drums &H36 &H01 &H37 &H11 &H38 &H11 ------------------------------------------------------------ ``` ## USAGE When using this information in, for example, an interrupt-driven music piece, you must take the following things into account. 1) When a new frequency is specified for an instrument, bit 4 of the corresponding register must first be switched off. To clarify: if a new frequency needs to be entered in channel 1, bit 4 of register &H10 must be cleared. After that the frequency is written, and finally bit 4 is set again (reg. &H10). For other channels a different register is used accordingly. 2) When an instrument is played that 'fades out' (Release), a short delay is needed in machine code: ```z80 LD B,3 ;approximately 3! LOOP: DJNZ LOOP ``` 3) The note frequencies are: ``` Note: LSB MSB (bit 0 of reg &H20-&H28) --------------------------------------------------------- C &HAD 0 C# &HB7 0 D &HC2 0 D# &HCD 0 E &HD9 0 F &HE6 0 F# &HF4 0 G &H03 1 G# &H12 1 A &H22 1 A# &H34 1 B &H46 1 --------------------------------------------------------- ``` With this information you should now be able to control the MSX-MUSIC system through these registers. Good luck! by R.M. (Just to be clear: I don't know who R.M. is, but it's not me! - RM-FCS)