GEEKSPEAK U: The Yamaha FM Chips of Gaming - Part 6 of 12: OPL Intro / YM3526 (aka OPL)

We've looked already at the OPM chip, and at the OPN line of chips in this series. The last series of chips that we'll focus on is the OPL line. The OPL line was mostly used on computer sound cards (such as the Ad-Lib, and Sound Blasters), but also did show up quite a bit in arcade games (mostly in conjunction with a YM2203 - OPN), and the budget version of the OPL line, the OPLL (YM2413) did show up in home gaming.

Where the OPM and the OPN line have quite a lot more in common than distinct, the OPL line is quite a bit of a departure from the OPM/OPN chips. And as we'll see, that will involve some MAJOR weaknesses against OPM/OPN, but also some pretty serious advantages as well. While the first three chips in the OPL line we will look at are widely regarded as inferior to the OPM/OPN chips, the final two OPL chips we will look at are widely regarded as quite superior to them.

The thing the first three chips in the OPL line (YM3526 - OPL, YM3812 - OPL2, and YM2413 - OPLL) all have the following in common: a) they are ONLY two-operator per channel, which means they can't do the more complex, nuanced FM that the four-operator OPM and OPN chips can do, and b) what they have going for them is they have a higher FM channel count than any of the OPM/OPN chips (plus another set of advantages that we'll get into with the OPL2).

All three of these chips have the same channel counts and options: They can either have nine channels of non-percussive FM instruments, or they can have six channels of non-percussive FM instruments PLUS five channels of FM percussion (also "canned" like the OPNA, only FM, rather than ADPCM) for a total of eleven channels instead of nine. And it's all pure FM (since none of the chips in the entire OPL line have any kind of PSG, and only the very last one (YMF278 - OPL4) had any kind of sampling capabilities.)

What separates the OPL from the OPL2 and beyond is that the OPL can only use sine operators like the OPM and OPN chips (but again, only 2-op, instead of 4.)

So, like the OPN and OPM, it's limited to just sine operators on the one hand, while like the OPL2, and OPLL, it's limited to just two operators per channel, on the other.

While this is indeed a "worst of both worlds" situation OPL found itself in, it also makes the chip really interesting and valuable as ANY sound that can be made by the OPL can also be made by ANY other chip in our series. So it makes a GREAT baseline referent for FM music - if you hear a sound on any other chip that sounds like a sound you heard on the OPL, then regardless of the additional capabilities of that chip, you know you're hearing a two-op, sine-only voice). It also means that ANY of the chips in the series can make sounds that this chip can not (so if you hear a sound that you haven't heard on OPL, there's a very good chance that it's something other than a two-op, sine-only voice).

In this way, the OPL is THE MOST basic chip of the entire series in that it is the one that is the most limited in terms of its FM generating capabilities on a channel-per-channel basis. However, once again, its saving grace is that it has such a high number of channels - three-way tying for a first place that would not be bested until the advent of the OPL3. By contrast, the OPN could do complex 4-op FM, but only had a paltry three FM channels (one third the OPL's massive channel count). Hence why these two chips were often paired together in the arcade.

Anyway, here are two games that use just the OPL for music - Terra Cresta, and Booby Kids. In fact, these are the only games I could find besides Fire Trap which I could confirm ONLY uses OPL for music. I will include Fire Trap as well, but it'll be actual game play rather than a music video, meaning it'll also have sound effects.

Here's Terra Cresta

Here's Booby Kids

And here's Fire Trap - but again, you're gonna have to deal with sound effects, and the like. Sorry I couldn't find a music-only video.

GEEKSPEAK U: The Yamaha FM chips of Gaming - Part 2 of 12: OPN series intro and YM2203 (OPN)

The OPN line had several chips that were used. While they varied greatly in terms of how many FM channels they had, what kind of sampling and/or PSG capabilities they had, and the number of total channels they had, they all had this one thing in common with each other: their FM channels were all four-operator, eight algorithm, sine-only. Which means "on-an-individual-channel-per-channel-basis", the entire OPN line were all equals*. OPM had some advantages over the OPN line, namely the second detune parameters, and the beefier LFO. But sharing the sine-only four-op, eight-algo thing definitely put OPM and the OPN line more or less in the same ballpark in terms of raw "on-an-individual-channel-per-channel-basis" FM capabilities.

The first chip in the OPN line, the YM2203 (called "OPN") only had three FM channels, and no sampling capabilities, but it did have an entire YM2149 PSG built in. YM2149 is essentially identical to a General Instruments AY-3-8910, which had three pulse wave channels (almost exclusively using plain square waves), and one noise channel. Though this is a series about FM, and this is an "FM chip", it really is just as much a "PSG" chip, and that's the side of the house that will actually get more talk time in this post:

The YM2149/AY-3-8910 chip was very comparable to the NES' 2AO3 in terms of its pulse width options. NES had four modes, with a total of three timbres (since two of them sound identical to each other, and are thus redundant), 12.5%, 25%, 50% (square), and 75% (redundant to 25%). The AY/YM had 25%, 50%, and 85%, though again, the 50% plain square was almost exclusively used. Both had very good noise channels. And both could use periodic noise musically (though I don't think NES ever did this, except for the metallic voices in Quick Man (Mega Man 2)). I believe AY/YM used this mode more often. Both AY/YM and 2A03 could pitch themselves comparably deep.

The biggest difference between the two is a) NES is two pulse, one triangle, and the AY/YM is three pulse, and b) the NES, albeit a very, very crappy one, and not frequently used, had a dedicated PCM sampler channel, and the AY/YM did not. If it was going to sample, it had to do it by tricking the periodic noise to do it, which sounded even worse than the NES's crappy sampler, and tied up a channel, where all four of NES's "normal" channels would still be free during sampling. One advantage to the AY/YM, though, is that its square waves had this great haunting quality to them that the crisper NES lacked.

Anyway, that's the AY/YM vs NES in a nutshell, and the basics of the YM2203 (OPN) FM chip as well. I know we spent more time talking PSG than FM in this post, but as I said above, it really is about an equal component in this very "FM/PSG-duet" sounding chip, and the FM side, between what was already said in the OPM post, and the remainder of this series will be fleshed out quite nicely.

OPN appeared in several arcade games, and also in the NEC PC 88/98. Our examples are the Y's I and II soundtracks for the PC88, composed by the legend - Yuzo Koshiro, the Sorcerian PC88 Soundtrack and a standalone track from Advanced Power Dolls 2 for the PC98.

The first three are more typical examples of the OPN's sound, though the Advanced Power Dolls 2 track shows that the OPN is actually capable of quite a bit more advanced sounding things - in fact, I had originally thought I was listening to the OPNA, because I thought the drums were sampled - nope...FM. Also I thought there might've been more than three FM channels happening at once, but again....nope. You really can do some pretty amazing things on the OPN!

Ys I

Ys II

Sorcerian

Advanced Power Dolls 2 - PC98 - Believe in Motivation (composed by Hiroto Saitoh)

GEEKSPEAK U: The Yamaha FM chips of Gaming - Part 1 of 12: Introduction + OPM (YM2151)

While Yamaha had several lines of chips that either "were", or at least "had" FM, for pre-fifth generation gaming, only three lines were used, OPM, OPL, and OPN. Each chip had a chip name, and then a name identifying what series it was from, and its relation to the rest of the series.

The OPM "series" was not really a series, as it only had one chip, the YM2151....and it's series identifier....wait for it, waaaaaiiit for it: "OPM".

While there were several FM chips used in arcade games, this one was the most prolific, and probably the most powerful. This chip had limited use outside the arcade, as it was the principle chip used in the Sharp X68000, but for the most part, this was an Arcade chip.

It was an eight channel chip, each capable of up to four operators, and eight algorithm settings. It also had some special features, such as a secondary detune parameter, and an advanced LFO. It could only use sine wave operators (except for the LFO, which could use any basic waveform as well as noise), and did not have ANY sampling, or PSG capability. This wasn't a big problem though, since A) it was almost always paired with a sampler chip in the arcade, usually something from either Okidata's MSM line, or Sega's proprietary "SegaPCM" - the Sharp using an MSM, and B) it didn't really need PSG either since 1) FM can "fake a square wave" with two sine waves very convincingly, and 2) it had enough total channels that it could spare some to fake PSG, and still have enough for more serious FM applications.

Here's an example of the OPM - Shinobi (Arcade) Soundtrack:

Shinobi PCB had OPM and a sampler chip, but the sampler was used for voice clips and sound effects. As for the music: 100% pure unadulterated OPM FM!

And here are a few other examples for you (a mix of complete soundtracks and stand alone tracks) - all using the YM2151 OPM from either the Arcade, or from the Sharp X68000 (some also use PCM sampling for percussion, and some are pure FM). If you have any others you'd like to share, feel free to post away in the comments!

Akumajou Dracula (aka Castlevania) - X68000 OST - Load BGM

Area 88 (aka UN Squadron) - Arcade - Complete OST

Metal Orange EX - X68000 - Stage 1 Theme

Marble Madness - Arcade - Full OST

and lastly - Shadowland - Arcade - Full OST