Talk:General Instrument AY-3-8912

How different is the Texas Instruments SN76489 from this PSG? It looks about the same, 3 channels, square wave, noise generator... Only 4 octaves though, the other page says. Still... Maybe the design of the one is based on the other, something probably worth mentioning? Grauw 03:57, Mar 19, 2005 (UTC)

They are different chips and require different programming. The AY has three sound channels, any of which can have noise, tone or a combination of the two. The SN has three tone channels and one completely separate noise channel with coarser pitch adjustments. Another difference between the two is that the AY contains a number of hardware envelopes for sound adjustment whereas the SN does not have anything similar.

One should tidy up the facts a little bit here, regarding the numerical designations of this chip and its close family members (I suspect 8192<->8912 fumble...). Also, assert type of relationship with GI (General Instrument)'s 2nd source (?) chips (used in Intellivision and MSX).
--Wernher 22:11, 15 Nov 2003 (UTC)

Wheren't the YM and AY versions different regarding the volume scaling? As fas as i know, the AY scaled linear and the YM scaled logaritmical?

I don't know if you have this the wrong way around, but the AY definitely has pseudo-logarithmic volume scaling - see for example the sourcecode to the FUSE Spectrum emulator

Yeah, the volume scale of n = 0...15 for the AY pretty much translates to y = 2^-((15-n)/2) (although not very accurately). Grauw 21:09, Jun 17, 2005 (UTC)

I have composed several tunes on both the YM2149 inside the Atari ST and the AY present in Spectrum computers ... the volume scaling is different. The difference in volume on the YM from e.g. F to E is much higher than on the AY, which makes it possible on AY to make more subtle and expressive volumes. So maybe both volume scalings are logarithmic, but the YM's is way more logarithmic than the AY's :) Only real nerds hear the difference tho.--Drx 23:02, July 29, 2005 (UTC)