Utz, I'm impressed with your work.
I've done two modifications of Special FX engine.
In the first one I used the drum routine to play the AY basses as a third independent channel, but...
I wanted the music to be editable in Beepola, so the limit was 4 bass notes + AY mute.
I chose notes D, F, A and A# as the best synchronized and hard-wired them to drums 1-4.
Drum 5 is used as AY mute.
In the Beepola SFX editor you can use more drums, but only drums 1 to 5 are exported to asm music data.
You can use other notes, but the values of DRM patterns must be changed manually in a text editor
or if you want to use 4 different notes, simply change them in the asm for drums 1-4
The values in the DRM patterns are 129 - 132 for drums 1-4, 133 for AY mute, they are exported automatically.
The drums 6+ use higher values 134+
The test is the pattern 4. Notes E, F#, G, B are used as drums 6-9.
The original beeper drums may be added to the music, but carefully. When the AY note is changed, a drum is released.
That's why there are only beeper drums 1 and 3 arranged.
Separation of beeper drums and AY bass is possible, but it would require re-writing the engine, to store the data for drums and AY bass in separate columns or use bits of the tracker notation (if any bits are free).
The zip contains a Beepola tracker file, a ZX tape and assembly of the engine and music data.
The tape runs with USR 60000 (or RANDOMIZE USR 60000 on ZX48), This is only a short example to see that almost everything may be edited in Beepola.
Compile Beepola music as data only .asm, remove the ORG at the beginning and re-assembly with the DoomBass.
Post's attachmentsdoombass01.zip 6.19 kb, 7 downloads since 2016-08-02
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