diff --git a/papers/format.md b/papers/format.md
index 44faff0b2..54082b532 100644
--- a/papers/format.md
+++ b/papers/format.md
@@ -234,6 +234,7 @@ size | description
      |   - 0xce: Namco C140 - 24 channels
      |   - 0xcf: Namco C219 - 16 channels
      |   - 0xd0: Namco C352 - 32 channels (UNAVAILABLE)
+     |   - 0xd1: ESFM - 18 channels (UNAVAILABLE)
      |   - 0xde: YM2610B extended - 19 channels
      |   - 0xe0: QSound - 19 channels
      |   - 0xfc: Pong - 1 channel