diff --git a/src/main/java/com/loomcom/symon/devices/Acia6850.java b/src/main/java/com/loomcom/symon/devices/Acia6850.java
index 0eb7917..3621887 100644
--- a/src/main/java/com/loomcom/symon/devices/Acia6850.java
+++ b/src/main/java/com/loomcom/symon/devices/Acia6850.java
@@ -97,9 +97,9 @@ public class Acia6850 extends Acia {
 		}
 
         // Bit 7 controls receiver IRQ behavior
-        receiveIrqEnabled = (commandRegister & 0x80) == 0;
+        receiveIrqEnabled = (commandRegister & 0x80) != 0;
         // Bits 5 & 6 controls transmit IRQ behavior
-        transmitIrqEnabled = (commandRegister & 0x20) == 0 && (commandRegister & 0x40) != 0;
+        transmitIrqEnabled = (commandRegister & 0x20) != 0 && (commandRegister & 0x40) == 0;
     }
 
 
@@ -127,6 +127,8 @@ public class Acia6850 extends Acia {
 
     private synchronized void reset() {
 		overrun = false;
+        rxFull = false;
+        txEmpty = true;
     }
 
 }
diff --git a/src/test/java/com/loomcom/symon/AciaTest6850.java b/src/test/java/com/loomcom/symon/AciaTest6850.java
new file mode 100644
index 0000000..487bf53
--- /dev/null
+++ b/src/test/java/com/loomcom/symon/AciaTest6850.java
@@ -0,0 +1,145 @@
+package com.loomcom.symon;
+
+import com.loomcom.symon.devices.Acia;
+import com.loomcom.symon.devices.Acia6850;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.*;
+
+public class AciaTest6850 {
+    
+    private final static int CMD_STAT_REG = 0;
+    private final static int DATA_REG = 1;
+    
+    
+    private Acia newAcia() throws Exception {
+        Acia acia = new Acia6850(0x0000);
+        // by default rate is limited, have it unlimited for testing
+        acia.setBaudRate(0);
+        return acia;
+    }
+    
+
+    @Test
+    public void shouldTriggerInterruptOnRxFullIfRxIrqEnabled() throws Exception {
+        Bus mockBus = mock(Bus.class);
+
+        Acia acia = newAcia();
+        acia.setBus(mockBus);
+
+        // Disable TX IRQ, Enable RX IRQ
+        acia.write(CMD_STAT_REG, 0x80);
+
+        acia.rxWrite('a');
+
+        verify(mockBus, atLeastOnce()).assertIrq();
+    }
+
+    @Test
+    public void shouldNotTriggerInterruptOnRxFullIfRxIrqNotEnabled() throws Exception {
+        Bus mockBus = mock(Bus.class);
+
+        Acia acia = newAcia();
+        acia.setBus(mockBus);
+
+        // Disable TX IRQ, Disable RX IRQ
+        acia.write(CMD_STAT_REG, 0x00);
+
+        acia.rxWrite('a');
+
+        verify(mockBus, never()).assertIrq();
+    }
+
+    @Test
+    public void shouldTriggerInterruptOnTxEmptyIfTxIrqEnabled() throws Exception {
+        Bus mockBus = mock(Bus.class);
+
+        Acia acia = newAcia();
+        acia.setBus(mockBus);
+
+        // Enable TX IRQ, Disable RX IRQ
+        acia.write(CMD_STAT_REG, 0x20);
+
+        // Write data
+        acia.write(1, 'a');
+
+        verify(mockBus, never()).assertIrq();
+
+        // Transmission should cause IRQ
+        acia.txRead();
+
+        verify(mockBus, atLeastOnce()).assertIrq();
+    }
+
+    @Test
+    public void shouldNotTriggerInterruptOnTxEmptyIfTxIrqNotEnabled() throws Exception {
+        Bus mockBus = mock(Bus.class);
+
+        Acia acia = newAcia();
+        acia.setBus(mockBus);
+
+        // Disable TX IRQ, Disable RX IRQ
+        acia.write(CMD_STAT_REG, 0x02);
+
+        // Write data
+        acia.write(DATA_REG, 'a');
+
+        // Transmission should cause IRQ
+        acia.txRead();
+
+        verify(mockBus, never()).assertIrq();
+    }
+
+    @Test
+    public void newAciaShouldHaveTxEmptyStatus() throws Exception {
+        Acia acia = newAcia();
+
+        assertEquals(0x02, acia.read(CMD_STAT_REG) & 0x02);
+    }
+
+    @Test
+    public void aciaShouldHaveTxEmptyStatusOffIfTxHasData() throws Exception {
+        Acia acia = newAcia();
+
+        acia.txWrite('a');
+        assertEquals(0x00, acia.read(CMD_STAT_REG) & 0x02);
+    }
+
+    @Test
+    public void aciaShouldHaveRxFullStatusOnIfRxHasData() throws Exception {
+        Acia acia = newAcia();
+
+        acia.rxWrite('a');
+       
+        assertEquals(0x01, acia.read(CMD_STAT_REG) & 0x01);
+    }
+
+    @Test
+    public void aciaShouldHaveTxEmptyAndRxFullStatusOffIfRxAndTxHaveData()
+            throws Exception {
+        Acia acia = newAcia();
+       
+        acia.rxWrite('a');
+        acia.txWrite('b');
+
+        assertEquals(0x01, acia.read(CMD_STAT_REG) & 0x03);
+    }
+
+    @Test
+    public void readingBuffersShouldResetStatus()
+            throws Exception {
+        Acia acia = newAcia();
+
+        assertEquals(0x00, acia.read(CMD_STAT_REG) & 0x01);
+        
+        acia.rxWrite('a');
+        
+        assertEquals(0x01, acia.read(CMD_STAT_REG) & 0x01);
+        
+        acia.rxRead();
+        
+        assertEquals(0x00, acia.read(CMD_STAT_REG) & 0x01);        
+        
+    }
+}