--- nono/vm/extram.cpp	2026/04/29 17:05:17	1.1
+++ nono/vm/extram.cpp	2026/04/29 17:05:25	1.1.1.3
@@ -11,6 +11,7 @@
 // TS-6BE16 互換だと $0100'0000 〜 $01ff'ffff の 16MB。
 // 060turbo 互換だと $1000'0000 〜 $17ff'ffff の 128MB、
 //                   $1000'0000 〜 $1fff'ffff の 256MB。
+//                   $1000'0000 〜 $2fff'ffff の 512MB。(独自拡張)
 //
 
 // 拡張 RAM はロングワード単位でホストバイトオーダ配置なので、
@@ -49,15 +50,22 @@ ExtRAMDevice::Init()
 		break;
 	 case 128:
 	 case 256:
+	 case 384:
+	 case 512:
 		ram_addr = 0x10'000000;
 		break;
 	 default:
-		item.Err("Valid size is 16, 128, and 256 for now");
+		item.Err("Valid size are 16, 128, 256, 384 or 512 for now");
 		return false;
 	}
 
 	ram_size = extram_size_MB * 1024 * 1024;
-	ram.reset(new uint8[ram_size]);
+	ram.reset(new(std::nothrow) uint8[ram_size]);
+	if ((bool)ram == false) {
+		errno = ENOMEM;
+		warn("ExtRAM(%u bytes)", ram_size);
+		return false;
+	}
 
 	return true;
 }
@@ -78,34 +86,34 @@ ExtRAMDevice::Decoder(uint32 addr) const
 	return (addr - ram_addr);
 }
 
-uint64
+busdata
 ExtRAMDevice::Read8(uint32 addr)
 {
 	uint32 offset = Decoder(addr);
-	uint32 data = ram[HLB(offset)];
-	putlog(4, "$%08x.B -> $%02x", addr, data);
+	busdata data = ram[HLB(offset)];
+	putlog(4, "$%08x.B -> $%02x", addr, data.Data());
 	return data;
 }
 
-uint64
+busdata
 ExtRAMDevice::Read16(uint32 addr)
 {
 	uint32 offset = Decoder(addr);
-	uint32 data = *(uint16 *)&ram[HLW(offset)];
-	putlog(4, "$%08x.W -> $%04x", addr, data);
+	busdata data = *(uint16 *)&ram[HLW(offset)];
+	putlog(4, "$%08x.W -> $%04x", addr, data.Data());
 	return data;
 }
 
-uint64
+busdata
 ExtRAMDevice::Read32(uint32 addr)
 {
 	uint32 offset = Decoder(addr);
-	uint32 data = *(uint32 *)&ram[offset];
-	putlog(4, "$%08x.L -> $%08x", addr, data);
+	busdata data = *(uint32 *)&ram[offset];
+	putlog(4, "$%08x.L -> $%08x", addr, data.Data());
 	return data;
 }
 
-uint64
+busdata
 ExtRAMDevice::Write8(uint32 addr, uint32 data)
 {
 	uint32 offset = Decoder(addr);
@@ -114,7 +122,7 @@ ExtRAMDevice::Write8(uint32 addr, uint32
 	return 0;
 }
 
-uint64
+busdata
 ExtRAMDevice::Write16(uint32 addr, uint32 data)
 {
 	uint32 offset = Decoder(addr);
@@ -123,7 +131,7 @@ ExtRAMDevice::Write16(uint32 addr, uint3
 	return 0;
 }
 
-uint64
+busdata
 ExtRAMDevice::Write32(uint32 addr, uint32 data)
 {
 	uint32 offset = Decoder(addr);
@@ -132,19 +140,19 @@ ExtRAMDevice::Write32(uint32 addr, uint3
 	return 0;
 }
 
-uint64
+busdata
 ExtRAMDevice::Peek8(uint32 addr)
 {
 	uint32 offset = Decoder(addr);
 	return ram[HLB(offset)];
 }
 
-uint64
+bool
 ExtRAMDevice::Poke8(uint32 addr, uint32 data)
 {
 	if ((int32)data >= 0) {
 		uint32 offset = Decoder(addr);
 		ram[HLB(offset)] = data;
 	}
-	return 0;
+	return true;
 }