No, not really, but this should get you going... You can use CHCPU routine like this:

LD A,L00000MM
JP #180

L=1 Update CPU LED
L=0 Don't update CPU LED

MM=0 Z80 ROM
MM=1 R800 ROM
MM=2 R800 DRAM

If you need to access Z80 DRAM mode, use CHCPU to switch to Z80 ROM and then do:

OUT &HE4,6: OUT &HE5,32

ROM:s are in last memory mapper pages:
#FC = BIOS (0-0 #0000-#3FFF)
#FD = BASIC (0-0 #4000-#7FFF)
#FE = SUBROM (3-1 #0000-#3FFF)
#FF = Kanji ROM (3-1 #4000-#7FFF)

could you use this feature in order to include a small segment
of code that echoes the psg on the scc in a given slot?

WYZ showed that the effect can be great

main ideas are here
http://karoshi.msxgamesbox.com/index.php?topic=562.0

In this way we can have scc support in any psg only game!!!!!!

Just read the AY registers and copy them adjusting a bit
in the scc registers

this is the code to add to the interrupt:

SCCOUT:     ;FRECUENCIA

            ld  a,0x3fh
            ld  (Bank3),a

            LD  HL,(AYREGS+0)       ;REPRODUCE SONIDO EN SCC
            LD  (SCC_REG+0),HL
            DEC HL                  ;CHORUS EN CANAL 4 OPCIONAL
            LD  (SCC_REG+6),HL      ;*
            LD  HL,(AYREGS+2)
            LD  (SCC_REG+2),HL
            DEC HL                  ;CHORUS EN CANAL 5 OPCIONAL
            DEC HL
            LD  (SCC_REG+8),HL      ;*
            LD  HL,(AYREGS+4)
            LD  (SCC_REG+4),HL

            ;VOLUMEN

            LD      A,(AYREGS+8)
            LD      (SCC_REG+0x0A),A
            LD      (SCC_REG+0x0D),A
            LD      A,(AYREGS+9)
            LD      (SCC_REG+0x0B),A
            LD      (SCC_REG+0x0E),A
            LD      A,(AYREGS+10)
            LD      (SCC_REG+0x0C),A
            

            ;MIXER
            ld a,(AYREGS+AR_Mixer)
            ld  b,a
            xor a
            bit 0,b
            jp nz,noA
            or  00001001B       ; A-> ch 1 & 4
noA:        bit 1,b
            jp  nz,noB
            or  00010010B       ; B-> ch 2 & 5
noB:        bit 2,b
            jp  nz,noC
            or  00000100B       ; C-> ch 3
noC:        ld (SCC_REG+0x0F),a
            
            RET

the sole problem is the scc init, but it can be solved

Quote:

could you use this feature in order to include a small segment of code that echoes the psg on the scc in a given slot?

Yes, go to http://www.msx.fi/nyyrikki/software.html and search for "PSG emulator for SCC Ver: 1.0"

Although this only patches BIOS routines it could be made to read PSG as well... How ever I'm not sure I can find the sources anymore... 10 years is a long time...

actually the difference are the CHORUS effects
that make the music a lot better
And if you read the psg you are sure that any
game will work.

moreover we could have the instruments vary
using a key....

So with "CHORUS" you mean detuning the voice and playing it one other channel, or do you mean something more complex?

that is chorus! even nicer when the two channels have also different waves