diff --git a/Components/6850/6850.cpp b/Components/6850/6850.cpp
index 4776cb1a8..d59f5c971 100644
--- a/Components/6850/6850.cpp
+++ b/Components/6850/6850.cpp
@@ -9,6 +9,7 @@
 #include "6850.hpp"
 
 #define LOG_PREFIX "[6850] "
+#define NDEBUG
 #include "../../Outputs/Log.hpp"
 
 using namespace Motorola::ACIA;
@@ -145,6 +146,7 @@ void ACIA::consider_transmission() {
 		// Output all that.
 		const int total_bits = 1 + data_bits_ + stop_bits_ + (parity_ != Parity::None);
 		transmit.write(divider_ * 2, total_bits, transmission);
+		printf("Transmitted %02x [%03x]\n", next_transmission_, transmission);
 
 		// Mark the transmit register as empty again.
 		next_transmission_ = NoValue;
diff --git a/Components/SerialPort/SerialPort.cpp b/Components/SerialPort/SerialPort.cpp
index 3d903154d..5e80b4be9 100644
--- a/Components/SerialPort/SerialPort.cpp
+++ b/Components/SerialPort/SerialPort.cpp
@@ -31,7 +31,7 @@ void Line::advance_writer(int cycles) {
 
 			if(old_level != level_) {
 				if(read_delegate_) {
-					read_delegate_->serial_line_did_change_output(this, Storage::Time(write_cycles_since_delegate_call_, clock_rate_), level_);
+					read_delegate_->serial_line_did_change_output(this, Storage::Time(write_cycles_since_delegate_call_, clock_rate_), old_level);
 					write_cycles_since_delegate_call_ = 0;
 				}
 			}
@@ -89,11 +89,11 @@ void Line::flush_writing() {
 		}
 
 		if(new_level != level_) {
-			level_ = new_level;
 			if(read_delegate_) {
 				read_delegate_->serial_line_did_change_output(this, Storage::Time(write_cycles_since_delegate_call_, clock_rate_), level_);
 				write_cycles_since_delegate_call_ = 0;
 			}
+			level_ = new_level;
 		}
 	}
 	events_.clear();
diff --git a/Components/SerialPort/SerialPort.hpp b/Components/SerialPort/SerialPort.hpp
index 5f8628588..d4a2ac98a 100644
--- a/Components/SerialPort/SerialPort.hpp
+++ b/Components/SerialPort/SerialPort.hpp
@@ -55,7 +55,7 @@ class Line {
 		bool read();
 
 		struct ReadDelegate {
-			virtual void serial_line_did_change_output(Line *line, Storage::Time time_since_last_change, bool new_level) = 0;
+			virtual void serial_line_did_change_output(Line *line, Storage::Time time_since_last_change, bool old_level) = 0;
 		};
 		void set_read_delegate(ReadDelegate *delegate);
 
diff --git a/Machines/AtariST/AtariST.cpp b/Machines/AtariST/AtariST.cpp
index c13c352bc..a5ccfe9c8 100644
--- a/Machines/AtariST/AtariST.cpp
+++ b/Machines/AtariST/AtariST.cpp
@@ -42,22 +42,23 @@ class IntelligentKeyboard:
 			input.set_read_delegate(this);
 		}
 
-		void serial_line_did_change_output(Serial::Line *, Storage::Time time_since_last_change, bool new_level) final {
+		void serial_line_did_change_output(Serial::Line *, Storage::Time time_since_last_change, bool old_level) final {
 			// Figure out how many bits have passed. TODO: in fixed point?
 			const float number_of_bits = time_since_last_change.get<float>() * 7812.5f + bit_offset_;
 			bit_offset_ = fmodf(number_of_bits, 1.0f);
+			printf("Changed from %d after %d bits\n", old_level, int(number_of_bits));
 
 			int bits_remaining = int(number_of_bits);
 			while(bits_remaining--) {
 				if(!bit_count_) {
 					// Check for a potential start bit.
-					if(!new_level) {
-						bit_count_ = 10;
+					if(!old_level) {
+						bit_count_ = 9;
 						command_ = 0;
 					}
 				} else {
 					command_ >>= 1;
-					command_ |= new_level ? 0 : 0x200;
+					command_ |= old_level ? 0x200 : 0x000;
 					--bit_count_;
 
 					if(!bit_count_) {