diff --git a/InstructionSets/x86/Instruction.cpp b/InstructionSets/x86/Instruction.cpp
index 57b76c04a..0f1bc62db 100644
--- a/InstructionSets/x86/Instruction.cpp
+++ b/InstructionSets/x86/Instruction.cpp
@@ -141,6 +141,7 @@ std::string InstructionSet::x86::to_string(Operation operation, DataSize size) {
 
 		default:
 			assert(false);
+			return "";
 	}
 }
 
diff --git a/InstructionSets/x86/Instruction.hpp b/InstructionSets/x86/Instruction.hpp
index a50abc24d..1467defcf 100644
--- a/InstructionSets/x86/Instruction.hpp
+++ b/InstructionSets/x86/Instruction.hpp
@@ -83,7 +83,7 @@ enum class Operation: uint8_t {
 
 	/// Reads from the port specified by source to the destination.
 	IN,
-	/// Writes from the port specified by destination from the source.
+	/// Writes to the port specified by destination from the source.
 	OUT,
 
 	// Various jumps; see the displacement to calculate targets.
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 352f0ad27..81c6ba4b8 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -8,6 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		423BDC4A2AB24699008E37B6 /* 8088Tests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 423BDC492AB24699008E37B6 /* 8088Tests.mm */; };
+		42437B332AC70833006DFED1 /* HDV.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B6FD0342923061300EC4760 /* HDV.cpp */; };
 		4281683A2A37AFB4008ECD27 /* DispatcherTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 428168392A37AFB4008ECD27 /* DispatcherTests.mm */; };
 		42A5E80C2ABBE04600A0DD5D /* NeskellTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 42A5E80B2ABBE04600A0DD5D /* NeskellTests.swift */; };
 		42A5E8442ABBE16F00A0DD5D /* illegal_rmw_test.bin in Resources */ = {isa = PBXBuildFile; fileRef = 42A5E8332ABBE16F00A0DD5D /* illegal_rmw_test.bin */; };
@@ -6329,6 +6330,7 @@
 				4B778F4323A5F1B00000D260 /* ImplicitSectors.cpp in Sources */,
 				4B7752B128217EA30073E2C5 /* StaticAnalyser.cpp in Sources */,
 				4B778F5123A5F2290000D260 /* StaticAnalyser.cpp in Sources */,
+				42437B332AC70833006DFED1 /* HDV.cpp in Sources */,
 				4B7752C028217F3D0073E2C5 /* Line.cpp in Sources */,
 				4B7C7A00282C3BCA002D6C0B /* 68000flamewingTests.mm in Sources */,
 				4B778F0223A5EBA40000D260 /* MFMSectorDump.cpp in Sources */,
diff --git a/OSBindings/Mac/Clock SignalTests/8088Tests.mm b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
index 7ff618037..1efe32904 100644
--- a/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
@@ -146,7 +146,9 @@ std::string to_string(
 - (NSArray<NSString *> *)testFiles {
 	NSString *path = [NSString stringWithUTF8String:TestSuiteHome];
 	NSSet *allowList = [NSSet setWithArray:@[
-//		@"F6.7.json.gz",
+		// Failing CALL and JMP.
+//		@"FF.3.json.gz",
+//		@"FF.5.json.gz",
 	]];
 
 	// Unofficial opcodes; ignored for now.
@@ -250,6 +252,34 @@ std::string to_string(
 			operation += to_string(instruction.source(), instruction, offsetLength, immediateLength, InstructionSet::x86::DataSize::DWord);
 		break;
 
+		case Operation::IN:
+			operation += " ";
+			operation += to_string(instruction.destination(), instruction, offsetLength, immediateLength);
+			operation += ", ";
+			switch(instruction.source().source()) {
+				case Source::DirectAddress:
+					operation += to_hex(instruction.offset(), 2, true);
+				break;
+				default:
+					operation += to_string(instruction.source(), instruction, offsetLength, immediateLength, InstructionSet::x86::DataSize::Word);
+				break;
+			}
+		break;
+
+		case Operation::OUT:
+			operation += " ";
+			switch(instruction.destination().source()) {
+				case Source::DirectAddress:
+					operation += to_hex(instruction.offset(), 2, true);
+				break;
+				default:
+					operation += to_string(instruction.destination(), instruction, offsetLength, immediateLength, InstructionSet::x86::DataSize::Word);
+				break;
+			}
+			operation += ", ";
+			operation += to_string(instruction.source(), instruction, offsetLength, immediateLength);
+		break;
+
 		// Rolls and shifts list eCX as a source on the understanding that everyone knows that rolls and shifts
 		// use CL even when they're shifting or rolling a word-sized quantity.
 		case Operation::RCL:	case Operation::RCR: