diff --git a/InstructionSets/ARM/Executor.hpp b/InstructionSets/ARM/Executor.hpp
index b867fe82c..20ccad951 100644
--- a/InstructionSets/ARM/Executor.hpp
+++ b/InstructionSets/ARM/Executor.hpp
@@ -42,7 +42,7 @@ struct NullStatusHandler {
 template <Model model, typename MemoryT, typename StatusObserverT = NullStatusHandler>
 struct Executor {
 	template <typename... Args>
-	Executor(StatusObserverT &observer, Args &&...args) : status_observer_(observer), bus(std::forward<Args>(args)...) {}
+	Executor(StatusObserverT &observer, Args &&...args) : bus(std::forward<Args>(args)...), status_observer_(observer) {}
 
 	template <typename... Args>
 	Executor(Args &&...args) : bus(std::forward<Args>(args)...) {}
@@ -327,7 +327,7 @@ struct Executor {
 			}
 		} else {
 			bool did_read;
-			uint32_t value;
+			uint32_t value = 0;
 
 			if constexpr (flags.transfer_byte()) {
 				uint8_t target;
@@ -480,7 +480,7 @@ struct Executor {
 			// undo the previous load.
 			struct {
 				uint32_t *target = nullptr;
-				uint32_t value;
+				uint32_t value = 0;
 			} last_replacement;
 
 			for(uint32_t c = 0; c < total; c++) {
diff --git a/InstructionSets/ARM/Registers.hpp b/InstructionSets/ARM/Registers.hpp
index d85bf6440..31bab96ab 100644
--- a/InstructionSets/ARM/Registers.hpp
+++ b/InstructionSets/ARM/Registers.hpp
@@ -272,6 +272,7 @@ struct Registers {
 				case Condition::GT:	return !le();
 				case Condition::LE:	return le();
 
+				default:
 				case Condition::AL:	return true;
 				case Condition::NV:	return false;
 			}
@@ -351,6 +352,7 @@ struct Registers {
 			}
 
 			switch(mode_) {
+				default:
 				case Mode::User: return active_[offset];
 
 				case Mode::Supervisor:
diff --git a/Machines/Acorn/Archimedes/Archimedes.cpp b/Machines/Acorn/Archimedes/Archimedes.cpp
index e8e7f8895..b352ddb89 100644
--- a/Machines/Acorn/Archimedes/Archimedes.cpp
+++ b/Machines/Acorn/Archimedes/Archimedes.cpp
@@ -34,15 +34,13 @@
 #include <set>
 #include <vector>
 
-namespace {
-
-Log::Logger<Log::Source::Archimedes> logger;
-
-}
-
 namespace Archimedes {
 
 #ifndef NDEBUG
+namespace {
+Log::Logger<Log::Source::Archimedes> logger;
+}
+
 template <InstructionSet::ARM::Model model, typename Executor>
 struct HackyDebugger {
 	void notify(uint32_t address, uint32_t instruction, Executor &executor) {
@@ -452,7 +450,7 @@ class ConcreteMachine:
 		int video_divider_ = 1;
 
 		void tick_cpu() {
-			uint32_t instruction;
+			uint32_t instruction = 0;
 			if(!executor_.bus.read(executor_.pc(), instruction, executor_.registers().mode(), false)) {
 //				logger.info().append("Prefetch abort at %08x; last good was at %08x", executor_.pc(), last_pc);
 				executor_.prefetch_abort();
diff --git a/Machines/Acorn/Archimedes/MemoryController.hpp b/Machines/Acorn/Archimedes/MemoryController.hpp
index f76b6c91c..6e91b8ef2 100644
--- a/Machines/Acorn/Archimedes/MemoryController.hpp
+++ b/Machines/Acorn/Archimedes/MemoryController.hpp
@@ -71,13 +71,10 @@ struct MemoryController {
 
 	template <typename IntT>
 	bool write(uint32_t address, IntT source, InstructionSet::ARM::Mode, bool trans) {
-		// User mode may only _write_ to logically-mapped RAM (subject to further testing below).
-		if(trans && address >= 0x200'0000) {
-			return false;
-		}
-
 		switch(write_zones_[(address >> 21) & 31]) {
 			case Zone::DMAAndMEMC: {
+				if(trans) return false;
+
 				const auto buffer_address = [](uint32_t source) -> uint32_t {
 					return (source & 0x1'fffc) << 2;
 				};
@@ -110,6 +107,25 @@ struct MemoryController {
 						high_rom_access_time_ = ROMAccessTime((address >> 6) & 3);
 						low_rom_access_time_ = ROMAccessTime((address >> 4) & 3);
 						page_size_ = PageSize((address >> 2) & 3);
+						switch(page_size_) {
+							default:
+							case PageSize::kb4:
+								page_address_shift_ = 12;
+								page_adddress_mask_ = 0x0fff;
+							break;
+							case PageSize::kb8:
+								page_address_shift_ = 13;
+								page_adddress_mask_ = 0x1fff;
+							break;
+							case PageSize::kb16:
+								page_address_shift_ = 14;
+								page_adddress_mask_ = 0x3fff;
+							break;
+							case PageSize::kb32:
+								page_address_shift_ = 15;
+								page_adddress_mask_ = 0x7fff;
+							break;
+						}
 
 						logger.info().append("MEMC Control: %08x -> OS:%d sound:%d video:%d refresh:%d high:%d low:%d size:%d", address, os_mode_, sound_dma_enable_, video_dma_enable_, dynamic_ram_refresh_, high_rom_access_time_, low_rom_access_time_, page_size_);
 						map_dirty_ = true;
@@ -126,19 +142,23 @@ struct MemoryController {
 			} break;
 
 			case Zone::IOControllers:
+				if(trans) return false;
 				ioc_.template write<IntT>(address, source);
 			break;
 
 			case Zone::VideoController:
+				if(trans) return false;
 				// TODO: handle byte writes correctly.
 				ioc_.video().write(source);
 			break;
 
 			case Zone::PhysicallyMappedRAM:
+				if(trans) return false;
 				physical_ram<IntT>(address) = source;
 			break;
 
 			case Zone::AddressTranslator:
+				if(trans) return false;
 //				printf("Translator write at %08x; replaces %08x\n", address, pages_[address & 0x7f]);
 				pages_[address & 0x7f] = address;
 				map_dirty_ = true;
@@ -154,13 +174,9 @@ struct MemoryController {
 
 	template <typename IntT>
 	bool read(uint32_t address, IntT &source, InstructionSet::ARM::Mode, bool trans) {
-		// User mode may only read logically-maped RAM and ROM.
-		if(trans && address >= 0x200'0000 && address < 0x380'0000) {
-			return false;
-		}
-
 		switch (read_zones_[(address >> 21) & 31]) {
 			case Zone::PhysicallyMappedRAM:
+				if(trans) return false;
 				source = physical_ram<IntT>(address);
 			break;
 
@@ -184,6 +200,7 @@ struct MemoryController {
 			break;
 
 			case Zone::IOControllers:
+				if(trans) return false;
 				ioc_.template read<IntT>(address, source);
 			break;
 
@@ -298,6 +315,8 @@ struct MemoryController {
 			kb16 = 0b10,
 			kb32 = 0b11,
 		} page_size_ = PageSize::kb4;
+		int page_address_shift_ = 12;
+		uint32_t page_adddress_mask_ = 0xffff;
 
 		// Address translator.
 		//
@@ -339,33 +358,14 @@ struct MemoryController {
 			}
 			address = aligned<IntT>(address);
 			address &= 0x1ff'ffff;
-			size_t page;
-
-			// TODO: eliminate switch here.
-			switch(page_size_) {
-				default:
-				case PageSize::kb4:
-					page = address >> 12;
-					address &= 0x0fff;
-				break;
-				case PageSize::kb8:
-					page = address >> 13;
-					address &= 0x1fff;
-				break;
-				case PageSize::kb16:
-					page = address >> 14;
-					address &= 0x3fff;
-				break;
-				case PageSize::kb32:
-					page = address >> 15;
-					address &= 0x7fff;
-				break;
-			}
+			const size_t page = address >> page_address_shift_;
 
 			const auto &map = mapping<is_read>(trans, os_mode_);
 			if(!map[page]) {
 				return nullptr;
 			}
+
+			address &= page_adddress_mask_;
 			return reinterpret_cast<IntT *>(&map[page][address]);
 		}
 
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
index 19b54b90e..474fa352e 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
@@ -62,7 +62,7 @@
       </Testables>
    </TestAction>
    <LaunchAction
-      buildConfiguration = "Release"
+      buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       enableASanStackUseAfterReturn = "YES"
diff --git a/Storage/Disk/Track/PCMSegment.cpp b/Storage/Disk/Track/PCMSegment.cpp
index d01859ea3..e75c8715e 100644
--- a/Storage/Disk/Track/PCMSegment.cpp
+++ b/Storage/Disk/Track/PCMSegment.cpp
@@ -31,14 +31,21 @@ PCMSegmentEventSource::PCMSegmentEventSource(const PCMSegment &segment) :
 }
 
 PCMSegmentEventSource::PCMSegmentEventSource(const PCMSegmentEventSource &original) {
+	*this = original;
+}
+
+PCMSegmentEventSource &PCMSegmentEventSource::operator =(const PCMSegmentEventSource &original) {
 	// share underlying data with the original
 	segment_ = original.segment_;
 
 	// load up the clock rate and set initial conditions
 	next_event_.length.clock_rate = segment_->length_of_a_bit.clock_rate;
 	reset();
+
+	return *this;
 }
 
+
 void PCMSegmentEventSource::reset() {
 	// start with the first bit to be considered the zeroth, and assume that it'll be
 	// flux transitions for the foreseeable
diff --git a/Storage/Disk/Track/PCMSegment.hpp b/Storage/Disk/Track/PCMSegment.hpp
index f4a13e0d5..44b605989 100644
--- a/Storage/Disk/Track/PCMSegment.hpp
+++ b/Storage/Disk/Track/PCMSegment.hpp
@@ -163,6 +163,7 @@ class PCMSegmentEventSource {
 			but a unique pointer into it.
 		*/
 		PCMSegmentEventSource(const PCMSegmentEventSource &);
+		PCMSegmentEventSource &operator =(const PCMSegmentEventSource &);
 
 		/*!
 			@returns the next event that will occur in this event stream.