--- nono/vm/opm.h	2026/04/29 17:04:45	1.1.1.1
+++ nono/vm/opm.h	2026/04/29 17:05:14	1.1.1.5
@@ -4,27 +4,43 @@
 // Licensed under nono-license.txt
 //
 
+//
+// OPM (YM2151)
+//
+
 #pragma once
 
 #include "device.h"
+#include "event.h"
 
-class OPMDevice
-	: public IODevice
+class OPMDevice : public IODevice
 {
 	using inherited = IODevice;
- private:
+
 	static const int baseaddr = 0xe90000;
+	static const uint64 clk = 250_nsec;		// 4MHz
 
  public:
 	OPMDevice();
 	virtual ~OPMDevice() override;
 
+	void ResetHard(bool poweron) override;
+
  protected:
 	// BusIO インタフェース
 	static const uint32 NPORT = 2;
-	uint64 Read(uint32 addr);
-	uint64 Write(uint32 addr, uint32 data);
-	uint64 Peek(uint32 addr);
+	uint64 Read(uint32 offset);
+	uint64 Write(uint32 offset, uint32 data);
+	uint64 Peek(uint32 offset);
+
+ private:
+	bool IsBusy() const;
+
+	int reg {};		// アクセスレジスタ番号
+
+	uint64 busy_origin;		// BUSY の起点時刻
+	uint64 busy_start;		// BUSY のアサート開始時刻
+	uint64 busy_end;		// BUSY のアサート終了時刻
 };
 
-extern std::unique_ptr<OPMDevice> gOPM;
+extern OPMDevice *gOPM;