From 952578f15abab3da6d68664d2ad41fdff5a2c313 Mon Sep 17 00:00:00 2001
From: freq-mod <32672779+freq-mod@users.noreply.github.com>
Date: Sun, 9 Jul 2023 14:42:48 +0200
Subject: [PATCH] Update ay8910.md

---
 doc/7-systems/ay8910.md | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/doc/7-systems/ay8910.md b/doc/7-systems/ay8910.md
index 64e814825..c3f5e5dd9 100644
--- a/doc/7-systems/ay8910.md
+++ b/doc/7-systems/ay8910.md
@@ -46,3 +46,12 @@ as of Furnace 0.6pre7, AY-3-8910 supports software PCM, where all 3 channels can
   - this changes the port's mode to "write". make sure you have connected something to it.
 - `2Fxx`: **write to I/O port B.**
   - this changes the port's mode to "write". make sure you have connected something to it.
+
+# chip config
+## AY derivative modes
+
+ay-3-810 was an absurdly popular chip that was blessed with many third-party clones, lincenced or not.
+
+- the AY-3-8914 variant was used in Intellivision, which is pretty much an 8910 with 4 level envelope volume per channel and different register format.
+- Yamaha YM2149 was an AY-3-8910 clone released in 1983. it's almsot identical to AY with minor differences being: higher hardware envelope step resolution (16 vs 32), half-clock mode when voltage level is low, much stronger DC offset, cleaner but softer output.
+- Sunsoft 5B is YM2149 clone with half-clock mode forced on.