From 8f0952ae7a85193a33dcde60ede25fcb1d131841 Mon Sep 17 00:00:00 2001
From: kub <derkub@gmail.com>
Date: Fri, 27 Sep 2024 09:16:50 +0200
Subject: [PATCH] mcd, fix crash if no bios with msu

---
 pico/cd/memory.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pico/cd/memory.c b/pico/cd/memory.c
index 7699df296..72a64e4c8 100644
--- a/pico/cd/memory.c
+++ b/pico/cd/memory.c
@@ -1220,6 +1220,13 @@ static void m68k_mem_setup_cd(void);
 
 PICO_INTERNAL void PicoMemSetupCD(void)
 {
+  if (Pico_mcd == NULL) {
+    static u8 bios_id[4] = "SEGA";
+    PicoCreateMCD(NULL, 0);
+    // BIOS faking for MSU-MD, checks for "SEGA" at 0x400100 to detect CD drive
+    memcpy(Pico_mcd->bios+0x100, bios_id, 4);
+  }
+
   pcd_base_address = (Pico.romsize ? 0x400000 : 0x000000);
 
   // setup default main68k map