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last year i was trying to code some converters from .vgm to Furnace tracker clipboard (text) on several sound chips, sn76489 included

on the sn76489 i struggled to get frequency data from the noise channel - https://notabug.org/nitrofurano/vgm2vortextracker/raw/master/vgm2furnaceclipboar... (runs on sdlBasic)

i actually took a look at the documentation at https://www.smspower.org/Development/SN76489 , but i struggled a lot what was there - at first i was expecting that the noise channel worked like the 3 pulse channels but it doesn't, and the information there looks a bit "nonsense" for me... :S

so, how do you think i could improve the code for obtaining these noise channel values in a way that could be used on Furnace tracker, like works on the 3 pulse channels?

thanks in advance!

Noise frequency values are one of three “stock” frequencies or a fourth “use the third tone channel” value. How does Furnace represent these?

as notes (like A-4 for 440hz, i guess), exactly like tone channels
(sneventracker/famitracker handles it differently, i guess this is why you asked?)

(perhaps a closer and easier reference to that for comparing is when we use ay-3-8910 chip there instead, and switching tone/noise bits in the instruments, instead of choosing channels )

Furnace uses an effect to change how the noise channel works.

In one mode, channel 4 is limited to the three pitches it can select between on its own.

In the other mode, notes in channel 4 automatically set the pitch of channel 3.

@lidnariq you mean at the instrument macros?

I uploaded some screenshots of how to switch between the two noise tone modes on Furnace in another thread, here:

https://www.smspower.org/forums/19548-NoiseChannelPitchInVariousTrackers#125871

The official "documentation", such as it is, is here:

https://github.com/tildearrow/furnace/blob/master/doc/7-systems/sms.md

You can also use the „duty“ part of your instrument macro to switch between modes on a per tick basis. The values correspond with those of the aforementioned effect.

To be honest, I’m not too fond of the way Furnace handles input on the noise channel. While it sure is convenient to enter all notes on only one channel instead of juggling two, it abstracts too much from the way the chip actually works. I don’t really like how C, C# and D represent the three values of fixed mode, regardless of octave, but I understand that implementing a custom solution (like Mod2PSG2 for example) might be too much to ask from a multi system tracker.

Author	Message
nitrofurano Joined: 01 Aug 2012 Posts: 317 Location: Porto, Portugal	how can we get noise frequency data from sn76489 .vgm files? Posted: Sat Jun 10, 2023 4:53 pm
	last year i was trying to code some converters from .vgm to Furnace tracker clipboard (text) on several sound chips, sn76489 included on the sn76489 i struggled to get frequency data from the noise channel - https://notabug.org/nitrofurano/vgm2vortextracker/raw/master/vgm2furnaceclipboar... (runs on sdlBasic) i actually took a look at the documentation at https://www.smspower.org/Development/SN76489 , but i struggled a lot what was there - at first i was expecting that the noise channel worked like the 3 pulse channels but it doesn't, and the information there looks a bit "nonsense" for me... :S so, how do you think i could improve the code for obtaining these noise channel values in a way that could be used on Furnace tracker, like works on the 3 pulse channels? thanks in advance!

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14516 Location: London	Posted: Sun Jun 11, 2023 6:43 am
	Noise frequency values are one of three “stock” frequencies or a fourth “use the third tone channel” value. How does Furnace represent these?

nitrofurano Joined: 01 Aug 2012 Posts: 317 Location: Porto, Portugal	Posted: Sun Jun 11, 2023 1:18 pm
	as notes (like A-4 for 440hz, i guess), exactly like tone channels (sneventracker/famitracker handles it differently, i guess this is why you asked?) (perhaps a closer and easier reference to that for comparing is when we use ay-3-8910 chip there instead, and switching tone/noise bits in the instruments, instead of choosing channels )

lidnariq Joined: 24 Mar 2021 Posts: 111	Posted: Sun Jun 11, 2023 6:41 pm
lidnariq Joined: 24 Mar 2021 Posts: 111	Furnace uses an effect to change how the noise channel works. In one mode, channel 4 is limited to the three pitches it can select between on its own. In the other mode, notes in channel 4 automatically set the pitch of channel 3.

nitrofurano Joined: 01 Aug 2012 Posts: 317 Location: Porto, Portugal	Posted: Sun Jun 11, 2023 9:59 pm
	@lidnariq you mean at the instrument macros?

willbritton Joined: 06 Mar 2022 Posts: 493 Location: London, UK	Posted: Sun Jun 11, 2023 11:20 pm
	I uploaded some screenshots of how to switch between the two noise tone modes on Furnace in another thread, here: https://www.smspower.org/forums/19548-NoiseChannelPitchInVariousTrackers#125871 The official "documentation", such as it is, is here: https://github.com/tildearrow/furnace/blob/master/doc/7-systems/sms.md

Kagesan Joined: 01 Feb 2014 Posts: 793	Posted: Mon Jun 12, 2023 6:15 pm
Kagesan Joined: 01 Feb 2014 Posts: 793	You can also use the „duty“ part of your instrument macro to switch between modes on a per tick basis. The values correspond with those of the aforementioned effect. To be honest, I’m not too fond of the way Furnace handles input on the noise channel. While it sure is convenient to enter all notes on only one channel instead of juggling two, it abstracts too much from the way the chip actually works. I don’t really like how C, C# and D represent the three values of fixed mode, regardless of octave, but I understand that implementing a custom solution (like Mod2PSG2 for example) might be too much to ask from a multi system tracker.

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