SPSG VST SID effect >> MIDI >> VGM  proof of concept...!
Here we go, this is a quick test with the PSG clocked at 1Mhz, only one channel and SID modulation..
http://www.alyjameslab.com/tempdata/midi_export2.vgz
you never got an SN76489 vgm with that
the greatest accuracy for exporting a midi file with the SPSG modulation as been made through Reaper at 22050 PPQN.

This looks really cool! I just got FMDRIVE but I may have to pick this up sometime soon as well. Thanks for the great Sega VST's!

I've spent the past few hours playing with the VST. I'm really impressed! This thing is insane. The custom timer stuff is just mind blowing. It uses chip emulation as a baseline, gets that perfect, and then adds things that wouldn't be possible without a DAW. It's a big contrast to the Plogue Chipsounds "jack of all trades, master of none" approach.

MAN, you da best! Really going to have to add the SN76489 'synth' to my to-do list!!
Yogi

SID sound...Timer modulation implemented on SN76489 MIDI board & in SPSG VST >> http://chipmusic.org/forums/topic/12578 … ded-synth/
The idea is to enhance the variety of sound, producing tones that the chip normally cannot produce to make some cool music!

Compatible with the SN76489 (code heavily modified!) open source arduino code by Littlescale
The code will be available for free of course to anybody wanting to mess around.
When use in conjunction with the MIDI device, SPSG vst will act as a controller with volume/pitch envelope generator and table!

PREVIEW

Of course I will add that you can also write to the volume register at CPU speed without using Hblank timing.
Writing this sequence of data for a 16 data point sinewave,
.db 04,02,01,00,00,01,02,04,11,13,14,15,15,14,13,11
gave me something like 1978Hz without any wait...
this gives us roughly a 31,648 KHz sample rate, it should be the same thing for PWM or PCM sample reading...assuming there isn't any other code going round then the audio stuff.
So it is twice as fast as Hblank with near 32µs against 64µs
the simplest square wave could be .db 00,15 as high as 15824Hz
anyway at high rate things get screwed up easily

Thanks I had to dig into YM2612 Timers for The FMDrive Vsti witch features CSM mode "speech synthesis control" ^_^
PM me  what you are working on unless it is top secret

Just making sure. As a guy working on a sound driver (or three) and enjoys doing research on the MD and co., I've been more than a little surprised at how few people are even remotely familiar with the YM2612's timers, so I'm glad you're familiar with them and at least made an informed design decision.

I'll probably chime in again if I find something useful to contribute. Otherwise, good luck on your project.

VBlank happens 50 times per second (for PAL)
HBlank happens 15625 times per second
So it should keep triggering

I have read that the Master System often use the Interrupt mode 1, meaning that when an interrupt occurs the Z80's PC register is set to $0038.
As you get only one entry, you have to choose whether you want VBlank or Hblank...

First reason is because I tried to emulate the Master System features
However AFAIK, YM2612 Timers do not cause interrupts and we must check the counting elsewhere.
Timer A is the only one fast enough, it is 10bits and goes as fast as 18µs at 1111111111 but only goes down to 54Hz at 0000000000
slightly better then Hblank 64µs.
Timer A can also be in use by the CSM mode witch screw up the ability to have both.

Keep in mind that my aim here was to check what could be done on the real thing before integrating the feature in my Super PSG Vsti.
I am in no way an expert on the Z80 side and if someone got a better way to increase the artificial waveform pitch resolution, let me know

AFAIK, no.
but I think it could be implemented directly in the firmware
You can still make this kind of PWM with two PSG channel slightly detuned.

I'm working on... something like this... for the Gameboy and I'm wondering if there aren't more flexible timers than HBlank on the MD Z80? Also, does the HBlank interrupt keep triggering during the VBlank period?

So good to see that there are more people taking some serious interest in the capabilities of the MD in terms of sound. Been a bit lonely in the MD scene to see everyone using the same drivers and never try new stuff with the hardware, and I applaud your efforts.

I am curious, though: Why did you choose to use the HBlank for timing? Could instead use one of the YM2612's internal timers to provide a much more flexible berth for timing than the HBlank's rigid timing.

Amazeful work. Man that UI is smooth .

This is very cool, so does GENMDM already support this sort of HBlank trick to reproduce this effect?