That's the YM3014B. It's the DAC that accompanies the OPL2 to turn the digital output into analog waveforms.

Thanks! Do you happen to know what some of the other chips on this card do? I'm guessing that some must be for the "ISA bus interfacing". Thanks.

Yup, AdLib didn't want others to clone the card so easily, so they removed the markings.
Didn't work obviously, because the Killer Card, aka Sound Blaster was released.

retro games 100 wrote:

Do you happen to know what some of the other chips on this card do? I'm guessing that some must be for the "ISA bus interfacing".

Yes, the AdLib is a really simple card.
There's the YM3812 aka OPL2, the YM3014B DAC, and that covers the actual synthesizer. There's an LM386 chip, which is the power amplifier, connected to an RC4136 op-amp.
The rest is the interface to the ISA bus. Decoding accesses to port 388h and 389h basically. Nothing else. Simple 74xx logic chips.

Thanks a lot! 😀 And also, thanks very much to everyone on this awesome website who answers my questions about vintage PC hardware - it's greatly appreciated.

By the way, I forgot one thing:
The 74xx chips also convert the base NTSC frequency of 14.28 MHz to 3.58 MHz for the OPL2 chip.

Scali wrote:

By the way, I forgot one thing:
The 74xx chips also convert the base NTSC frequency of 14.28 MHz to 3.58 MHz for the OPL2 chip.

How does it do that? By the use of the flip flops?

root42 wrote:

How does it do that? By the use of the flip flops?

I guess so, sergey's clone uses a 74LS74 to generate the clock:
https://docs.google.com/viewer?a=v&pid=sites& … NWQ5N2VjNjczYjg

I suppose the real one uses the 74LS109 for it?

Scali wrote:

I guess so, sergey's clone uses a 74LS74 to generate the clock: https://docs.google.com/viewer?a=v&pid=sites& … NWQ5N2VjNjczYjg […]
Show full quote

root42 wrote:

How does it do that? By the use of the flip flops?

I guess so, sergey's clone uses a 74LS74 to generate the clock:
https://docs.google.com/viewer?a=v&pid=sites& … NWQ5N2VjNjczYjg

I suppose the real one uses the 74LS109 for it?

I think this is the same as on the Sound Blaster / Snark Barker. It also uses the 74LS74 for dividing the ISA OSC by four:

http://tubetime.us/index.php/2019/01/19/sound … s-of-operation/

btw, was the 1987 Adlib card the very first FM music sound card for the PC? Thanks!

retro games 100 wrote:

btw, was the 1987 Adlib card the very first FM music sound card for the PC? Thanks!

Not entirely clear.
The IBM Music Feature Card (designed and made by Yamaha) was also introduced in 1987, so it may have been sooner:
https://en.wikipedia.org/wiki/IBM_Music_Feature_Card

watch vimeo clip embedded in this article for some more adlib background https://www.pcgamer.com/author-of-sound-blast … ys-of-pc-audio/
tldr: clueless is the best word to describe that company