From 71fe92daed87ba1f6ead953d2f50c8c1f94ea8e3 Mon Sep 17 00:00:00 2001
From: win2kgamer <47463859+win2kgamer@users.noreply.github.com>
Date: Tue, 21 Oct 2025 20:34:09 -0500
Subject: [PATCH] AD1848: I23 bits 7-1 are read-only on CS4232/4236 non-B,
 fixes CS4236 non-B detection on Windows 2000

---
 src/sound/snd_ad1848.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/sound/snd_ad1848.c b/src/sound/snd_ad1848.c
index ebfa9423b..c25890c50 100644
--- a/src/sound/snd_ad1848.c
+++ b/src/sound/snd_ad1848.c
@@ -521,6 +521,8 @@ readonly_x:
                     }
                     if (ad1848->type == AD1848_TYPE_CS4231) /* I23 is reserved and read-only on CS4231 non-A */
                         goto readonly_i;
+                    if ((ad1848->type >= AD1848_TYPE_CS4232) || (ad1848->type <= AD1848_TYPE_CS4236)) /* I23 bits 7-1 are read-only on CS4231A/4232/4236 non-B, Win2k relies on this for detection */
+                        val = (val & 0x01);
                     break;
 
                 case 24: