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#1 2016-03-21 19:42:55

Propheteer
Bloody beginner
From: Bonkersville, Delirium
Registered: 2014-10-15
Posts: 3

MIDI clock / MIDI timing & differences between PAL/NTSC C64's

Hello,

As some of you might have noticed upon running certain sequences or MIDI commands with MSSIAH in MIDI mode, it has a tendency to lag behind a tiny bit at times - let's say, depending on the amount of MIDI data that's being sent to MSSIAH, anywhere between ~10-30+ms - sometimes it's unnoticeable and definitely depends on the setup.

From what I've understood, very briefly put - the C64 architecture in itself wasn't obviously originally built for real-time MIDI input data handling & audio reproduction, even though MIDI 1.0 standard which came is supposed to be "low bandwith" (https://en.wikipedia.org/wiki/MIDI_1.0#Low_bandwidth). Remember that Atari ST in 1985 was the first home computer to actually support MIDI natively and it is still considered by some to be one of the most rock-solid MIDI master/clock units there are (i.e http://www.synthtopia.com/content/2010/03/10/atari-ste/).

This made me wonder: it is often noted with classic computers (and same-era game consoles as well) that the NTSC versions of many games had the tendency to run faster than PAL ones (or depending on the area of origin in which the program/game was developed, sometimes it was vice versa). The disparity is the 50/60Hz (PAL/NTSC) difference, which is based on the AC current & voltage difference in PAL vs. NTSC regions and so on, etc etc .. Add on top the changes/timing fixes often needed in the original program code whenever doing a port from PAL to NTSC or vice versa (more on the subject for example at http://unusedino.de/ec64/technical/misc … -ntsc.html)

Or, just check out this Youtube link where you can see and hear that the C64 audio speed and pitch can vary up to around 20% when comparing the PAL and NTSC versions of the same game! https://www.youtube.com/watch?v=UCvrTXrl0EI

Anyway, could it be possible that the altogether timing difference between PAL and NTSC units could also be observable in MSSIAH cartridges and/or other C64 MIDI modules? When running a MIDI cartridge in MIDI slave mode, is there any difference in latency if one would compare PAL vs. NTSC C64's? Any observations? Or am I just talking nonsense here? smile Let me know if I am. All thoughts are welcome!

Last edited by Propheteer (2016-03-21 19:44:13)

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