diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1d853e99f..b8c62544d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -620,7 +620,6 @@ target_sources(${PROJECT_NAME} PRIVATE
         core/hw/arm7/arm7_rec.cpp
         core/hw/arm7/arm7_rec.h
         core/hw/arm7/arm-new.h
-        core/hw/arm7/vbaARM.cpp
         core/hw/bba/bba.h
         core/hw/bba/bba.cpp
         core/hw/bba/rtl8139c.h
diff --git a/core/emulator.cpp b/core/emulator.cpp
index 52656209a..4b2db021c 100644
--- a/core/emulator.cpp
+++ b/core/emulator.cpp
@@ -342,7 +342,7 @@ void dc_reset(bool hard)
 	sh4_sched_reset(hard);
 	pvr::reset(hard);
 	libAICA_Reset(hard);
-	libARM_Reset(hard);
+	aicaarm::reset();
 	sh4_cpu.Reset(true);
 	mem_Reset(hard);
 }
@@ -404,7 +404,7 @@ void Emulator::init()
 
 	pvr::init();
 	libAICA_Init();
-	libARM_Init();
+	aicaarm::init();
 	mem_Init();
 	reios_init();
 
@@ -591,7 +591,6 @@ void Emulator::term()
 		sh4_cpu.Term();
 		custom_texture.Terminate();	// lr: avoid deadlock on exit (win32)
 		reios_term();
-		libARM_Term();
 		libAICA_Term();
 		pvr::term();
 		mem_Term();
diff --git a/core/hw/arm7/vbaARM.cpp b/core/hw/arm7/vbaARM.cpp
deleted file mode 100644
index f905ec0e7..000000000
--- a/core/hw/arm7/vbaARM.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-// nullAICA.cpp : Defines the entry point for the DLL application.
-//
-
-#include "arm7.h"
-
-//called when plugin is used by emu (you should do first time init here)
-s32 libARM_Init()
-{
-	aicaarm::init();
-
-	return 0;
-}
-
-//called when plugin is unloaded by emu, only if dcInit is called (eg, not called to enumerate plugins)
-void libARM_Term()
-{
-	//arm7_Term ?
-}
-
-//It's supposed to reset anything
-void libARM_Reset(bool hard)
-{
-	aicaarm::reset();
-	aicaarm::enable(false);
-}
diff --git a/core/hw/holly/sb_mem.cpp b/core/hw/holly/sb_mem.cpp
index 986d9a45d..e56ddd80b 100644
--- a/core/hw/holly/sb_mem.cpp
+++ b/core/hw/holly/sb_mem.cpp
@@ -353,7 +353,10 @@ T DYNACALL ReadMem_area0(u32 paddr)
 	default:
 		// G2 Ext area
 		if (System == DC_PLATFORM_NAOMI || System == DC_PLATFORM_NAOMI2)
-			return (T)libExtDevice_ReadMem_A0_010(addr, sz);
+		{
+			INFO_LOG(MEMORY, "Read<%d> from G2 Ext area not implemented @ %08x", sz, addr);
+			return (T)0;
+		}
 		else if (config::EmulateBBA)
 			return (T)bba_ReadMem(addr, sz);
 		else
@@ -466,12 +469,12 @@ void DYNACALL WriteMem_area0(u32 paddr, T data)
 	default:
 		// G2 Ext area
 		if (System == DC_PLATFORM_NAOMI || System == DC_PLATFORM_NAOMI2)
-			libExtDevice_WriteMem_A0_010(addr, data, sz);
+			INFO_LOG(MEMORY, "Write<%d> to G2 Ext area not implemented @ %08x: %x", sz, addr, (u32)data);
 		else if (config::EmulateBBA)
 			bba_WriteMem(addr, data, sz);
 		return;
 	}
-	INFO_LOG(COMMON, "Write to area0_32 not implemented [Unassigned], addr=%x,data=%x,size=%d", addr, data, sz);
+	INFO_LOG(MEMORY, "Write to area0_32 not implemented [Unassigned], addr=%x,data=%x,size=%d", addr, data, sz);
 }
 
 //Init/Res/Term
diff --git a/core/hw/naomi/naomi.h b/core/hw/naomi/naomi.h
index 514d4c67f..60ea8ded4 100644
--- a/core/hw/naomi/naomi.h
+++ b/core/hw/naomi/naomi.h
@@ -27,3 +27,6 @@ extern u32 reg_dimm_parameterh;
 extern u32 reg_dimm_status;
 
 void initdFFBInit();
+
+u32  libExtDevice_ReadMem_A0_006(u32 addr, u32 size);
+void libExtDevice_WriteMem_A0_006(u32 addr, u32 data, u32 size);
diff --git a/core/hw/sh4/dyna/shil.h b/core/hw/sh4/dyna/shil.h
index ac9932fc3..6cfa32f13 100644
--- a/core/hw/sh4/dyna/shil.h
+++ b/core/hw/sh4/dyna/shil.h
@@ -112,10 +112,7 @@ struct shil_param
 	bool is_r32() const { return is_r32i() || is_r32f(); }
 	bool is_r64() const { return is_r64f(); }	//just here for symmetry ...
 
-	bool is_imm_s8() const { return is_imm() && is_s8(_imm); }
-	bool is_imm_u8() const { return is_imm() && is_u8(_imm); }
-	bool is_imm_s16() const { return is_imm() && is_s16(_imm); }
-	bool is_imm_u16() const { return is_imm() && is_u16(_imm); }
+	bool is_imm_s8() const { return is_imm() && (s8)_imm == (s32)_imm; }
 
 	u32* reg_ptr()  const { verify(is_reg()); return GetRegPtr(_reg); }
 	s32  reg_nofs()  const { verify(is_reg()); return (s32)((u8*)GetRegPtr(_reg) - (u8*)GetRegPtr(reg_xf_0)-sizeof(Sh4cntx)); }
diff --git a/core/hw/sh4/sh4_mem.cpp b/core/hw/sh4/sh4_mem.cpp
index 2555bd4fb..48b1bac95 100644
--- a/core/hw/sh4/sh4_mem.cpp
+++ b/core/hw/sh4/sh4_mem.cpp
@@ -90,14 +90,15 @@ static void map_area4(u32 base)
 template <class T>
 T DYNACALL ReadMem_extdev_T(u32 addr)
 {
-	return (T)libExtDevice_ReadMem_A5(addr, sizeof(T));
+	INFO_LOG(SH4, "Read ext. device (Area 5) undefined @ %08x", addr);
+	return (T)0;
 }
 
 //Write Ext.Device
 template <class T>
 void DYNACALL WriteMem_extdev_T(u32 addr,T data)
 {
-	libExtDevice_WriteMem_A5(addr, data, sizeof(T));
+	INFO_LOG(SH4, "Write ext. device (Area 5) undefined @ %08x: %x", addr, (u32)data);
 }
 
 _vmem_handler area5_handler;
diff --git a/core/hw/sh4/sh4_mmr.h b/core/hw/sh4/sh4_mmr.h
index d276ba43a..6d92dfc3c 100644
--- a/core/hw/sh4/sh4_mmr.h
+++ b/core/hw/sh4/sh4_mmr.h
@@ -1,7 +1,7 @@
 #pragma once
 #include <array>
 #include "types.h"
-#include "../sh4/sh4_if.h"
+#include "sh4_if.h"
 
 //For mem mapping
 void map_area7_init();
diff --git a/core/rend/gui.cpp b/core/rend/gui.cpp
index 2ddbc9860..af1431cf0 100644
--- a/core/rend/gui.cpp
+++ b/core/rend/gui.cpp
@@ -2649,18 +2649,17 @@ void gui_term()
 	}
 }
 
-int msgboxf(const char* text, unsigned int type, ...) {
+void fatal_error(const char* text, ...)
+{
     va_list args;
 
     char temp[2048];
-    va_start(args, type);
+    va_start(args, text);
     vsnprintf(temp, sizeof(temp), text, args);
     va_end(args);
     ERROR_LOG(COMMON, "%s", temp);
 
     gui_display_notification(temp, 2000);
-
-    return 1;
 }
 
 extern bool subfolders_read;
diff --git a/core/types.h b/core/types.h
index 5fad8efa0..8855f595c 100644
--- a/core/types.h
+++ b/core/types.h
@@ -202,14 +202,10 @@ void os_DebugBreak();
 #define stricmp strcasecmp
 #endif
 
-int msgboxf(const char* text, unsigned int type, ...);
+void fatal_error(const char* text, ...);
 
-#define MBX_OK                       0
-#define MBX_ICONEXCLAMATION          0
-#define MBX_ICONERROR                0
-
-#define verify(x) do { if ((x) == false){ msgboxf("Verify Failed  : " #x "\n in %s -> %s : %d", MBX_ICONERROR, (__FUNCTION__), (__FILE__), __LINE__); dbgbreak;}} while (false)
-#define die(reason) do { msgboxf("Fatal error : %s\n in %s -> %s : %d", MBX_ICONERROR,(reason), (__FUNCTION__), (__FILE__), __LINE__); dbgbreak;} while (false)
+#define verify(x) do { if ((x) == false){ fatal_error("Verify Failed  : " #x "\n in %s -> %s : %d", (__FUNCTION__), (__FILE__), __LINE__); dbgbreak;}} while (false)
+#define die(reason) do { fatal_error("Fatal error : %s\n in %s -> %s : %d", (reason), (__FUNCTION__), (__FILE__), __LINE__); dbgbreak;} while (false)
 
 
 //will be removed sometime soon
@@ -408,28 +404,6 @@ extern settings_t settings;
 #define VRAM_MASK settings.platform.vram_mask
 #define BIOS_SIZE settings.platform.bios_size
 
-inline bool is_s8(u32 v) { return (s8)v==(s32)v; }
-inline bool is_u8(u32 v) { return (u8)v==(s32)v; }
-inline bool is_s16(u32 v) { return (s16)v==(s32)v; }
-inline bool is_u16(u32 v) { return (u16)v==(u32)v; }
-
-// 0x00600000 - 0x006007FF [NAOMI] (modem area for dreamcast)
-u32  libExtDevice_ReadMem_A0_006(u32 addr,u32 size);
-void libExtDevice_WriteMem_A0_006(u32 addr,u32 data,u32 size);
-
-//Area 0 , 0x01000000- 0x01FFFFFF	[Ext. Device]
-static inline u32 libExtDevice_ReadMem_A0_010(u32 addr,u32 size) { return 0; }
-static inline void libExtDevice_WriteMem_A0_010(u32 addr,u32 data,u32 size) { }
-
-//Area 5
-static inline u32 libExtDevice_ReadMem_A5(u32 addr,u32 size){ return 0; }
-static inline void libExtDevice_WriteMem_A5(u32 addr,u32 data,u32 size) { }
-
-//ARM
-s32 libARM_Init();
-void libARM_Reset(bool hard);
-void libARM_Term();
-
 template<u32 sz>
 u32 ReadMemArr(const u8 *array, u32 addr)
 {
diff --git a/shell/libretro/libretro.cpp b/shell/libretro/libretro.cpp
index 67a2aa94b..7019f647c 100644
--- a/shell/libretro/libretro.cpp
+++ b/shell/libretro/libretro.cpp
@@ -2899,27 +2899,18 @@ static void retro_keyboard_event(bool down, unsigned keycode, uint32_t character
 	}
 }
 
-int msgboxf(const char* text, unsigned int type, ...)
+void fatal_error(const char* text, ...)
 {
 	if (log_cb)
 	{
 		va_list args;
 		char temp[2048];
-
-		switch (type)
-		{
-		case MBX_ICONERROR:
-			va_start(args, type);
-			vsprintf(temp, text, args);
-			va_end(args);
-			strcat(temp, "\n");
-			log_cb(RETRO_LOG_ERROR, temp);
-			break;
-		default:
-			break;
-		}
+		va_start(args, text);
+		vsprintf(temp, text, args);
+		va_end(args);
+		strcat(temp, "\n");
+		log_cb(RETRO_LOG_ERROR, temp);
 	}
-	return 0;
 }
 
 void os_DebugBreak()