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Over the years, I've read and heard a common complaint about the Master System's sonic and musical capabilities, due to the SN76489. What's wrong with SMS music? It is obvious that the YM2413 chip is richer sonically, but with the PSG chip, very notable soundtracks have been achieved: Robocop Vs. Terminator, Lemmings, Pit-Fighter, the complete Sonic saga, Parlour Games, Streets Of Rage II, Sagaia, California Games...

So what's wrong with the PSG chip? Was the Ricoh 2A03 really better?

There’s not really anything wrong with the PSG, but it’s a rather primitive sound chip. Its main disadvantages are the fixed duty cycle of the tone channels and the lack of a proper bass register.

The Ricoh 2A03 is better in a couple of ways. You can modulate the duty cycles of the square waves (albeit not as much as, say, on the C64's SID), which goes a long way when it comes to changing the mood of a track. The triangle wave channel can produce a decent bass. Then there’s the PCM channel that can play custom samples to enhance the music with. Additionally, custom chips in the cartridges could further enhance the musical abilities, a technique not available on the SMS.

Having only a single duty cycle limits the timbre palette available to composers way more than you'd initially think.

It's not just 4x less possible sounds than the 2A03, it's more like an order of magnitude less, because quickly cycling through duty cycles lets you mimic how the attack on real instruments has richer harmonic content than sustained notes. Each pairing of duty cycles has an unique sound, pretty much.

Personally, I find the lack of a dedicated period counter for the noise channel on the SN7 also particularly annoying. The three fixed noise periods all sound like weird coughs. You really do need to borrow square 3's period counter to get decent open hi-hat noises, for instance.

Kagesan wrote

Additionally, custom chips in the cartridges could further enhance the musical abilities, a technique not available on the SMS.

It should be noted that expansion audio is only available on the Famicom, not too unlike how OPLL sound was only available in Japanese SMSs.

Thank you for your clarifying answers, I didn't know about the technical details of both chips.

The Rico chip beats the SN pretty easily most of the time, the NES will always sound more iconic. The only advantage is that its noise channel can reach any frequency (albeit with a major caveat) unlike the Rico's noise channel which is quite limited in its range. The SN is a dirt simple sound chip that really isn't capable of much, this doesn't necessarily mean it can't crank out some dank square wave fire tho.

I've been composing for it in my spare time for a few years now and while it's a little frustrating given its limitations at times, its primitive nature makes it an excellent starter chip if one wants to dabble in the art of chiptune music. I started out with Deflemask but have since switched to Furnace and have never looked back, they are remarkably similar in their UIs so the migration was easy. Here are some basic principles I've learned;

*SN1 & SN2 (square 1 & 2) are fully independent and are best used for lead melodies.
*SN3 can be used for a partial background support melody when its not being used for SFX, but this can get complicated depending how you design your VGM.
*SN3 & SN4 (square 3 & noise channel) are tied together and the secret to the SN is fully understanding the relationship these two have with each other. (ps. its toxic, they really need to stop fighting each other and file for a divorce)

*The noise channel has 4 modes; free-range white, free-range periodic, 3-note white, 3-note periodic. White sounds like old TV static and periodic sounds like a buzzer.
*Free range enables the noise channel to reach any note at the cost of square 3's independence. Both can still be partially used in this mode but they can only play the same note at any given time. Although they can't play independent notes, they can still have independent volumes.
*3-note mode (most common for VGMs) separates square 3 & noise allowing them to work somewhat independently of each another. The major trade off is that the noise channel is limited to playing only 3 preset notes while square 3 can play any note at any given time. In Deflemask & Furnace they have this 3N mode input set to C, C# & D, though it sounds just like A-4, A-5 & A-6 when set in FR mode. I've tested this out on my Game Gear, Master System and various emus.
*There's roughly a 4 octave difference between square 3 and noise in FR mode, keep that in mind.

Here are some techniques I've learned;
*If your vgm is complicated and relies on FR mode and your song happens to use SN4 for any of the A-4/A-5/A-6 notes at any given moment, then there is small window of opportunity to switch it over to 3N for those notes, temporarily giving SN3 a brief chance to play other additional notes.

*In FR mode, you can create a 2 instrument combo for SN3 & SN4 to make weird strobe effects. Have the SN3 ins use a 2-tick volume strobe (high-low>>). Then have the SN4 ins use an opposite 2-tick volume strobe (low-high>>). Then finally have a 2-tick arpeggio in both instruments that switch to the same note in unison per tick, the results are kinda cool if done properly. I managed to arrange the airfield theme from The Rocketeer NES game and got it to sound mostly good on the SN.

*There's an odd way to get a "4th" note out of noise in 3N mode, just make an instrument with a rapid 1-tick phase reset. The end result is a bizarre off-tune note that resides somewhere in the B range. Similar effect if doing a rapid strobe of any of the C (A-4) periodic/white notes in 3N mode.

*Rapid strobe of the noise channel between white/periodic can also produce some interesting sounds too.

*The coolest thing I noticed is that you can make the SN play a psuedo sawtooth wave by playing SN1_C-3@0B + SN2 or SN3_C-4@07. You will see it in the oscilloscope when both channel outputs are combined.

*There was another stupid attempt I tried a while back to see if I could make a psuedo triangle wave using all 3 square channels but it failed miserably. It ended up sounding like an eerie chime effect instead. Using a single channel to strobe in the higher frequency range produces a "crystal chime" like sound effect.

*As for SN1 & 2... there's not much else to do other than rapid note/volume strobe patterns, I attempted this when trying to arrange the Labyrinth theme from the GBC game Shantae.

Modern trackers allow for easier composition techniques, you can also pull off some real 8bit voodoo on these old chips for the sake of a challenge. Furnace supports all revisions of the SN, even the Neo Geo Pocket derivative was recently added. Also disclaimer; most of the terminology I used (SN1-4, FR, 3N) isn't in any official documentation on the SN76489 chip, It's just slang terms I've coined to help with memorization purposes.

To add to the box of tricks, you can “seek” into the noise random sequence by playing a frame of silent noise at a given frequency and then unmute it (and maybe change the frequency). You can also do a limited version of this with the “standard” noise frequencies. This can get you different sounds but I don’t know if any trackers have a way to “macro” this rather than arrange it by hand.

The periodic noise mode is actually a 1/16 duty cycle and is thus exactly 4 octaves below the tone channel driving it. This is different on the SG-1000 and other systems using the SN76489. They also have different noise patterns, so take care if targeting those.

kaportza wrote

*3-note mode (most common for VGMs) separates square 3 & noise allowing them to work somewhat independently of each another.

well, in this mode they are *totally* independent in fact :)

yeah true, I probably should've worded it better, spelling things and describing things have always been a struggle for me lol.

Either way, the Ricoh and the SN have their unique quirks. The coolest thing with Furnace is that you can setup both sound chips side by side to make some really creative music using the best characteristics of both, like some sort of 8bit console duet. It gets even better if you configure the SN chip to the GG variant which adds stereo support.

It might be fun to take a “battling chips” SMS+NES chiptune and play it on real systems, using an ungodly controller port connection to synchronise them.

Author	Message
Ron_Stard Joined: 01 Apr 2008 Posts: 198 Location: Spain	What's wrong with PSG? Posted: Tue Oct 24, 2023 11:24 am
Ron_Stard Joined: 01 Apr 2008 Posts: 198 Location: Spain	Over the years, I've read and heard a common complaint about the Master System's sonic and musical capabilities, due to the SN76489. What's wrong with SMS music? It is obvious that the YM2413 chip is richer sonically, but with the PSG chip, very notable soundtracks have been achieved: Robocop Vs. Terminator, Lemmings, Pit-Fighter, the complete Sonic saga, Parlour Games, Streets Of Rage II, Sagaia, California Games... So what's wrong with the PSG chip? Was the Ricoh 2A03 really better?

Kagesan Joined: 01 Feb 2014 Posts: 895	Posted: Tue Oct 24, 2023 12:31 pm
Kagesan Joined: 01 Feb 2014 Posts: 895	There’s not really anything wrong with the PSG, but it’s a rather primitive sound chip. Its main disadvantages are the fixed duty cycle of the tone channels and the lack of a proper bass register. The Ricoh 2A03 is better in a couple of ways. You can modulate the duty cycles of the square waves (albeit not as much as, say, on the C64's SID), which goes a long way when it comes to changing the mood of a track. The triangle wave channel can produce a decent bass. Then there’s the PCM channel that can play custom samples to enhance the music with. Additionally, custom chips in the cartridges could further enhance the musical abilities, a technique not available on the SMS.

Trirosmos Joined: 26 Apr 2022 Posts: 38 Location: Brinstar, Zebes	Posted: Tue Oct 24, 2023 5:04 pm
	Having only a single duty cycle limits the timbre palette available to composers way more than you'd initially think. It's not just 4x less possible sounds than the 2A03, it's more like an order of magnitude less, because quickly cycling through duty cycles lets you mimic how the attack on real instruments has richer harmonic content than sustained notes. Each pairing of duty cycles has an unique sound, pretty much. Personally, I find the lack of a dedicated period counter for the noise channel on the SN7 also particularly annoying. The three fixed noise periods all sound like weird coughs. You really do need to borrow square 3's period counter to get decent open hi-hat noises, for instance. Kagesan wrote Additionally, custom chips in the cartridges could further enhance the musical abilities, a technique not available on the SMS. It should be noted that expansion audio is only available on the Famicom, not too unlike how OPLL sound was only available in Japanese SMSs.

Ron_Stard Joined: 01 Apr 2008 Posts: 198 Location: Spain	Posted: Wed Oct 25, 2023 12:36 pm
Ron_Stard Joined: 01 Apr 2008 Posts: 198 Location: Spain	Thank you for your clarifying answers, I didn't know about the technical details of both chips.

kaportza Joined: 14 Sep 2018 Posts: 52 Location: Earth	Posted: Sat Oct 28, 2023 3:54 am
kaportza Joined: 14 Sep 2018 Posts: 52 Location: Earth	The Rico chip beats the SN pretty easily most of the time, the NES will always sound more iconic. The only advantage is that its noise channel can reach any frequency (albeit with a major caveat) unlike the Rico's noise channel which is quite limited in its range. The SN is a dirt simple sound chip that really isn't capable of much, this doesn't necessarily mean it can't crank out some dank square wave fire tho. I've been composing for it in my spare time for a few years now and while it's a little frustrating given its limitations at times, its primitive nature makes it an excellent starter chip if one wants to dabble in the art of chiptune music. I started out with Deflemask but have since switched to Furnace and have never looked back, they are remarkably similar in their UIs so the migration was easy. Here are some basic principles I've learned; SN1 & SN2 (square 1 & 2) are fully independent and are best used for lead melodies. SN3 can be used for a partial background support melody when its not being used for SFX, but this can get complicated depending how you design your VGM. SN3 & SN4 (square 3 & noise channel) are tied together and the secret to the SN is fully understanding the relationship these two have with each other. (ps. its toxic, they really need to stop fighting each other and file for a divorce) The noise channel has 4 modes; free-range white, free-range periodic, 3-note white, 3-note periodic. White sounds like old TV static and periodic sounds like a buzzer. Free range enables the noise channel to reach any note at the cost of square 3's independence. Both can still be partially used in this mode but they can only play the same note at any given time. Although they can't play independent notes, they can still have independent volumes. 3-note mode (most common for VGMs) separates square 3 & noise allowing them to work somewhat independently of each another. The major trade off is that the noise channel is limited to playing only 3 preset notes while square 3 can play any note at any given time. In Deflemask & Furnace they have this 3N mode input set to C, C# & D, though it sounds just like A-4, A-5 & A-6 when set in FR mode. I've tested this out on my Game Gear, Master System and various emus. There's roughly a 4 octave difference between square 3 and noise in FR mode, keep that in mind. Here are some techniques I've learned; If your vgm is complicated and relies on FR mode and your song happens to use SN4 for any of the A-4/A-5/A-6 notes at any given moment, then there is small window of opportunity to switch it over to 3N for those notes, temporarily giving SN3 a brief chance to play other additional notes. In FR mode, you can create a 2 instrument combo for SN3 & SN4 to make weird strobe effects. Have the SN3 ins use a 2-tick volume strobe (high-low>>). Then have the SN4 ins use an opposite 2-tick volume strobe (low-high>>). Then finally have a 2-tick arpeggio in both instruments that switch to the same note in unison per tick, the results are kinda cool if done properly. I managed to arrange the airfield theme from The Rocketeer NES game and got it to sound mostly good on the SN. There's an odd way to get a "4th" note out of noise in 3N mode, just make an instrument with a rapid 1-tick phase reset. The end result is a bizarre off-tune note that resides somewhere in the B range. Similar effect if doing a rapid strobe of any of the C (A-4) periodic/white notes in 3N mode. Rapid strobe of the noise channel between white/periodic can also produce some interesting sounds too. The coolest thing I noticed is that you can make the SN play a psuedo sawtooth wave by playing SN1_C-3@0B + SN2 or SN3_C-4@07. You will see it in the oscilloscope when both channel outputs are combined. There was another stupid attempt I tried a while back to see if I could make a psuedo triangle wave using all 3 square channels but it failed miserably. It ended up sounding like an eerie chime effect instead. Using a single channel to strobe in the higher frequency range produces a "crystal chime" like sound effect. As for SN1 & 2... there's not much else to do other than rapid note/volume strobe patterns, I attempted this when trying to arrange the Labyrinth theme from the GBC game Shantae. Modern trackers allow for easier composition techniques, you can also pull off some real 8bit voodoo on these old chips for the sake of a challenge. Furnace supports all revisions of the SN, even the Neo Geo Pocket derivative was recently added. Also disclaimer; most of the terminology I used (SN1-4, FR, 3N) isn't in any official documentation on the SN76489 chip, It's just slang terms I've coined to help with memorization purposes.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Posted: Sat Oct 28, 2023 8:41 am
	To add to the box of tricks, you can “seek” into the noise random sequence by playing a frame of silent noise at a given frequency and then unmute it (and maybe change the frequency). You can also do a limited version of this with the “standard” noise frequencies. This can get you different sounds but I don’t know if any trackers have a way to “macro” this rather than arrange it by hand. The periodic noise mode is actually a 1/16 duty cycle and is thus exactly 4 octaves below the tone channel driving it. This is different on the SG-1000 and other systems using the SN76489. They also have different noise patterns, so take care if targeting those.

sverx Joined: 05 Sep 2013 Posts: 3936 Location: Stockholm, Sweden	Posted: Mon Oct 30, 2023 8:18 am
	kaportza wrote 3-note mode (most common for VGMs) separates square 3 & noise allowing them to work somewhat independently of each another. well, in this mode they are totally* independent in fact :)

kaportza Joined: 14 Sep 2018 Posts: 52 Location: Earth	Posted: Tue Oct 31, 2023 6:48 pm
kaportza Joined: 14 Sep 2018 Posts: 52 Location: Earth	yeah true, I probably should've worded it better, spelling things and describing things have always been a struggle for me lol. Either way, the Ricoh and the SN have their unique quirks. The coolest thing with Furnace is that you can setup both sound chips side by side to make some really creative music using the best characteristics of both, like some sort of 8bit console duet. It gets even better if you configure the SN chip to the GG variant which adds stereo support.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14939 Location: London	Posted: Tue Oct 31, 2023 9:25 pm
	It might be fun to take a “battling chips” SMS+NES chiptune and play it on real systems, using an ungodly controller port connection to synchronise them.

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