Is this theoretically possibile on msx 2?
http://chipmusic.org/forums/topic/12185/sega-psg-pulse-width-modulation-on-1-channel-with-z80-hblank/
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Is this theoretically possibile on msx 2?
http://chipmusic.org/forums/topic/12185/sega-psg-pulse-width-modulation-on-1-channel-with-z80-hblank/
Maybe on msx 2 the rtc in test mode is a better option than hblank because iirc this latter does not trigger while borders are plotted
umh, how can you trigger the ints with RTC?
Maybe on msx 2 the rtc in test mode is a better option than hblank because iirc this latter does not trigger while borders are plotted
Wouldn't that change you current time/date settings ?
@Pingpong, no, you can only do a loop that waits a given rtc increment to cycle
@Louthrax, yes this would change the time and date
@Louthrax, yes this would change the time and date
Argl, too bad! So we have a high-res timer on all MSX2 machines but it can't be used...
Was thinking about saving the RTC time before switching to test mode, then adjusting the time back after use by adding the delta divided by some constant (you just need not to reset the MSX in between!). That could also add a small delta in the current time...
Maybe on msx 2 the rtc in test mode is a better option than hblank because iirc this latter does not trigger while borders are plotted
It does, I use it in VGMPlay to get a 300Hz interrupt. However, the 1chipMSX is buggy.
(Note at 60 Hz there are 262 lines and at 50 Hz there are 313, and you can only specify line interrupts for 256 lines, so there is still a little gap.)
PWM is also done with the AY3 (YM2149 actually) on Atari ST. I think it is possible on MSX2, but tricky.
Wow, that sounds pretty awesome! Is it only possible with the power of the ST's CPU?
and its timers... this makes the difference
http://dev-docs.atariforge.org/files/MC68901.pdf
the sega demo does wobble when sliding the frequency, it sounds like something has lack of granularity and the notes would be out of tune.
the 9938 rate has potential. look here http://insidious6581.blogspot.de/
scroll to "The audio updates are done with the CIA timer at 200 times per second", check out the drum.
this rate below khz is about adsr vibrato arpeggio kind of things taken to increased rate and then new things can happen.
the nicest would be to run a whole player at this rate. players tend to spike at notes, and the note rate would not be increased, maybe the cpu load isnt that bad.
and maybe 150hz without opened borders is already touching this interesting zone.
Maybe on msx 2 the rtc in test mode is a better option than hblank because iirc this latter does not trigger while borders are plotted
It does, I use it in VGMPlay to get a 300Hz interrupt. However, the 1chipMSX is buggy.
(Note at 60 Hz there are 262 lines and at 50 Hz there are 313, and you can only specify line interrupts for 256 lines, so there is still a little gap.)
I want to add, instead of using line interrupts, you can also poll the HR flag. Nice 15kHz oscillation.
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