From 07a7abed30564041391be28de20c604c9dda4a24 Mon Sep 17 00:00:00 2001
From: freq-mod <32672779+freq-mod@users.noreply.github.com>
Date: Sun, 9 Jul 2023 14:16:19 +0200
Subject: [PATCH] Update ym2610b.md

---
 doc/7-systems/ym2610b.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/7-systems/ym2610b.md b/doc/7-systems/ym2610b.md
index 7428f6fbe..2911c2671 100644
--- a/doc/7-systems/ym2610b.md
+++ b/doc/7-systems/ym2610b.md
@@ -96,3 +96,9 @@ it is backward compatible with the original chip.
 - `5Dxx`: **set D2R/SR of operator 2.**
 - `5Exx`: **set D2R/SR of operator 3.**
 - `5Fxx`: **set D2R/SR of operator 4.**
+
+# system modes
+## extended channel 3
+in ExtCh mode, channel 3 is split into one column for each of its four operators. feedback and LFO levels are shared. the frequency of each operator may be controlled independently with notes and effects. this can be used for more polyphony or more complex sounds.
+
+all four operators are still combined according to the algorithm in use. for example, algorithm 7 acts as four independent sine waves. algorithm 4 acts as two independent 2op sounds. even with algorithm 0, placing a note in any operator triggers that operator alone.