diff --git a/Machines/Apple/ADB/ReactiveDevice.cpp b/Machines/Apple/ADB/ReactiveDevice.cpp
index 67396abf2..b21fe45d4 100644
--- a/Machines/Apple/ADB/ReactiveDevice.cpp
+++ b/Machines/Apple/ADB/ReactiveDevice.cpp
@@ -10,12 +10,46 @@
 
 using namespace Apple::ADB;
 
-ReactiveDevice::ReactiveDevice(Apple::ADB::Bus &bus) : device_id_(bus.add_device(this)) {}
+ReactiveDevice::ReactiveDevice(Apple::ADB::Bus &bus) : bus_(bus), device_id_(bus.add_device(this)) {}
 
 void ReactiveDevice::post_response(const std::vector<uint8_t> &&response) {
 	response_ = std::move(response);
+	microseconds_at_bit_ = 0.0;
+	bit_offset_ = -1;
 }
 
 void ReactiveDevice::advance_state(double microseconds) {
-	(void)microseconds;
+	// Do nothing if not in the process of posting a response.
+	if(response_.empty()) return;
+
+	// Otherwise advance time appropriately.
+	microseconds_at_bit_ += microseconds;
+
+	// Bit '-1' is the sync signal.
+	if(bit_offset_ == -1) {
+		bus_.set_device_output(device_id_, false);
+		if(microseconds_at_bit_ < 300) {
+			return;
+		}
+		microseconds_at_bit_ -= 300;
+		++bit_offset_;
+	}
+
+	// Advance the implied number of bits.
+	bit_offset_ += int(microseconds_at_bit_ / 100);
+	microseconds_at_bit_ -= double(bit_offset_ * 100.0);
+
+	// Check for end-of-transmission.
+	if(bit_offset_ >= int(response_.size() * 10)) {
+		bus_.set_device_output(device_id_, true);
+		response_.clear();
+		return;
+	}
+
+	// Otherwise pick an output level.
+	const int byte = bit_offset_ / 10;
+	const int bit = ((0x200 | (int(response_[size_t(byte)]) << 1)) >> (bit_offset_ % 10)) & 1;
+
+	constexpr double low_periods[] = {66, 33};
+	bus_.set_device_output(device_id_, microseconds_at_bit_ > low_periods[bit]);
 }
diff --git a/Machines/Apple/ADB/ReactiveDevice.hpp b/Machines/Apple/ADB/ReactiveDevice.hpp
index e9c92494d..ab7ade2c6 100644
--- a/Machines/Apple/ADB/ReactiveDevice.hpp
+++ b/Machines/Apple/ADB/ReactiveDevice.hpp
@@ -25,8 +25,12 @@ class ReactiveDevice: public Bus::Device {
 		void advance_state(double microseconds) override;
 
 	private:
+		Bus &bus_;
 		const size_t device_id_;
+
 		std::vector<uint8_t> response_;
+		int bit_offset_ = 0;
+		double microseconds_at_bit_ = 0;
 };
 
 }