A7800Hawk: Fix pokey 0x450 detection

Assets/gamedb/gamedb_a7800.txt

@@ -150,7 +150,7 @@ md5:980c35ae9625773a450aa7ef51751c04		Scrapyard Dog	A78		NTSC=true;board=1
 md5:53db322c201323fe2ca8f074c0a2bf86		Scrapyard Dog	A78		PAL=true;board=1		
 md5:b697d9c2d1b9f6cb21041286d1bbfa7f		Sentinel	A78		NTSC=true;board=1
 md5:5469b4de0608f23a5c4f98f331c9e75f		Sentinel	A78		PAL=true;board=1
-md5:9bd70c06d3386f76f8162881699a777a		Serpentine	A78		NTSC=true;board=1;RAM=16
+md5:9bd70c06d3386f76f8162881699a777a		Serpentine	A78		NTSC=true;board=1;RAM=16;Pokey_450=true
 md5:2d643ac548c40e58c99d0fe433ba4ba0		Sirius	A78		NTSC=true;board=1;RAM=16		
 md5:a84c1b2300fbfbf21b1c02387f613dad		Space Duel	A78		PAL=true;board=0		
 md5:771cb4609347657f63e6f0eb26036e35		Space Duel	A78		NTSC=true;board=0		

src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs

@@ -30,8 +30,8 @@ namespace BizHawk.Emulation.Common
 			FirmwareAndOption("91383B92745CC7CC4F15409AC5BC2C2F699A43F1", 163840, "SNES", "ST018", "st018.rom", "ST018 Rom");
 			FirmwareAndOption("79F5FF55DD10187C7FD7B8DAAB0B3FFBD1F56A2C", 262144, "PCECD", "Bios", "pcecd-3.0-(J).pce", "Super CD Bios (J)");
 			FirmwareAndOption("014881a959e045e00f4db8f52955200865d40280", 32768, "PCECD", "GE-Bios", "gecard.pce", "Games Express CD Card (Japan)");
-			FirmwareAndOption("D9D134BB6B36907C615A594CC7688F7BFCEF5B43", 4096, "A78", "Bios_NTSC", "7800NTSCBIOS.bin", "NTSC Bios");
-			//FirmwareAndOption("CE236581AB7921B59DB95BA12837C22F160896CB", 4096, "A78", "Bios_NTSC", "speed_bios.bin", "NTSC Bios speed");
+			//FirmwareAndOption("D9D134BB6B36907C615A594CC7688F7BFCEF5B43", 4096, "A78", "Bios_NTSC", "7800NTSCBIOS.bin", "NTSC Bios");
+			FirmwareAndOption("CE236581AB7921B59DB95BA12837C22F160896CB", 4096, "A78", "Bios_NTSC", "speed_bios.bin", "NTSC Bios speed");
 
 			FirmwareAndOption("5A140136A16D1D83E4FF32A19409CA376A8DF874", 16384, "A78", "Bios_PAL", "7800PALBIOS.bin", "PAL Bios");
 			FirmwareAndOption("A3AF676991391A6DD716C79022D4947206B78164", 4096, "A78", "Bios_HSC", "7800highscore.bin", "Highscore Bios");

src/BizHawk.Emulation.Cores/Consoles/Atari/A7800Hawk/A7800Hawk.IEmulator.cs

@@ -189,7 +189,7 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 			if (temp == 4)
 			{
 				// the pokey chip ticks at the nominal cpu speed, but is unaffected by cpu slowdown (I think)
-				if (is_pokey)
+				if (is_pokey || is_pokey_450)
 				{
 					pokey.Tick();
 					temp_s_pokey = pokey.sample();

src/BizHawk.Emulation.Cores/Consoles/Atari/A7800Hawk/A7800Hawk.IStatable.cs

@@ -43,6 +43,7 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 			ser.Sync("pal kara", ref PAL_Kara);
 			ser.Sync("Cart RAM", ref cart_RAM);
 			ser.Sync(nameof(is_pokey), ref is_pokey);
+			ser.Sync(nameof(is_pokey_450), ref is_pokey_450);
 			ser.Sync(nameof(left_toggle), ref left_toggle);
 			ser.Sync(nameof(right_toggle), ref right_toggle);
 			ser.Sync(nameof(left_was_pressed), ref left_was_pressed);

src/BizHawk.Emulation.Cores/Consoles/Atari/A7800Hawk/A7800Hawk.cs

@@ -41,6 +41,7 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 		public bool PAL_Kara = false;
 		public int cart_RAM = 0;
 		public bool is_pokey = false;
+		public bool is_pokey_450 = false;
 
 		private readonly ITraceable _tracer;
 
@@ -142,7 +143,6 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 				if (dict.ContainsKey("RAM"))
 				{
 					int.TryParse(dict["RAM"], out cart_RAM);
-					Console.WriteLine(cart_RAM);
 				}
 
 				if (dict.ContainsKey("Pokey"))
@@ -150,6 +150,11 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 					bool.TryParse(dict["Pokey"], out is_pokey);
 				}
 
+				if (dict.ContainsKey("Pokey_450"))
+				{
+					bool.TryParse(dict["Pokey_450"], out is_pokey_450);
+				}
+
 				// some games will not function with the high score bios
 				// if such a game is being played, tell the user and disable it
 				if (dict.ContainsKey("No_HS"))
@@ -187,8 +192,8 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 					{
 						cart_RAM = 8;
 
-						// the homebrew game serpentine requires extra RAM, seems to use bit 6 to indicate this
-						if (cart_2.Bit(6))
+						// the homebrew game serpentine requires extra RAM, but in the alternative style
+						if (hash_md5 == "md5:9BD70C06D3386F76F8162881699A777A")
 						{
 							cart_RAM = 16;
 						}
@@ -200,6 +205,9 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 				}
 
 				if (cart_2.Bit(0)) { is_pokey = true; }
+
+				// the homebrew game serpentine requires the pokey chip to be available at the alternative location 0x450
+				if (cart_2.Bit(6)) { is_pokey_450 = true; }
 			}
 			else
 			{

src/BizHawk.Emulation.Cores/Consoles/Atari/A7800Hawk/Mappers/MapperSG.cs

@@ -1,5 +1,6 @@
 using BizHawk.Common;
 using BizHawk.Common.NumberExtensions;
+using System;
 
 namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 {
@@ -28,6 +29,14 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 				{
 					return Core._hsbios[addr - 0x3000];
 				}
+				else if (Core.is_pokey_450 && (addr >= 0x450) && (addr < 0x480))
+				{
+					if (addr < 0x460)
+					{
+						return Core.pokey.ReadReg(addr & 0xF);
+					}
+					return 0;
+				}
 
 				return Core.RAM[0x800 + addr & 0x7FF];
 			}
@@ -112,6 +121,13 @@ namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
 				if (addr >= 0x3000 && Core._hsbios != null)
 				{
 				}
+				else if (Core.is_pokey_450 && (addr >= 0x450) && (addr < 0x480))
+				{
+					if (addr < 0x460)
+					{
+						Core.pokey.WriteReg(addr & 0xF, value);
+					}					
+				}
 				else
 				{
 					Core.RAM[0x800 + addr & 0x7FF] = value;