ALU working, design needs updating + writing testbenches

11 files changed, 511 insertions, 220 deletions

diff --git a/alu/alu.srcs/sim_1/twoc_tb.vhd b/alu/alu.srcs/sim_1/twoc_tb.vhd
new file mode 120000
index 0000000..312c499
--- /dev/null
+++ b/alu/alu.srcs/sim_1/twoc_tb.vhd
@@ -0,0 +1 @@
+../../../src/twoc_tb.vhd
\ No newline at end of file
diff --git a/alu/alu.xpr b/alu/alu.xpr
index 5953561..db0f577 100644
--- a/alu/alu.xpr
+++ b/alu/alu.xpr
@@ -59,7 +59,7 @@
     <Option Name="IPStaticSourceDir" Val="$PIPUSERFILESDIR/ipstatic"/>
     <Option Name="EnableBDX" Val="FALSE"/>
     <Option Name="DSABoardId" Val="basys3"/>
-    <Option Name="WTXSimLaunchSim" Val="4"/>
+    <Option Name="WTXSimLaunchSim" Val="34"/>
     <Option Name="WTModelSimLaunchSim" Val="0"/>
     <Option Name="WTQuestaLaunchSim" Val="0"/>
     <Option Name="WTIesLaunchSim" Val="0"/>
@@ -206,6 +206,13 @@
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
+      <File Path="$PSRCDIR/sim_1/twoc_tb.vhd">
+        <FileInfo>
+          <Attr Name="AutoDisabled" Val="1"/>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
       <Config>
         <Option Name="DesignMode" Val="RTL"/>
         <Option Name="TopModule" Val="ALU_TB"/>
diff --git a/design/2c.dig b/design/2c.dig
index e553a6d..15349da 100644
--- a/design/2c.dig
+++ b/design/2c.dig
@@ -15,7 +15,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="520" y="500"/>
+      <pos x="500" y="500"/>
     </visualElement>
     <visualElement>
       <elementName>Out</elementName>
@@ -29,7 +29,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="680" y="500"/>
+      <pos x="800" y="500"/>
     </visualElement>
     <visualElement>
       <elementName>Not</elementName>
@@ -66,28 +66,89 @@
       </elementAttributes>
       <pos x="580" y="540"/>
     </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Input Splitting</string>
+          <string>8</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>7-7</string>
+        </entry>
+      </elementAttributes>
+      <pos x="540" y="580"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Cout</string>
+        </entry>
+      </elementAttributes>
+      <pos x="800" y="540"/>
+    </visualElement>
+    <visualElement>
+      <elementName>NOr</elementName>
+      <elementAttributes/>
+      <pos x="700" y="520"/>
+    </visualElement>
   </visualElements>
   <wires>
     <wire>
+      <p1 x="680" y="560"/>
+      <p2 x="700" y="560"/>
+    </wire>
+    <wire>
       <p1 x="580" y="500"/>
       <p2 x="600" y="500"/>
     </wire>
     <wire>
       <p1 x="660" y="500"/>
-      <p2 x="680" y="500"/>
+      <p2 x="800" y="500"/>
+    </wire>
+    <wire>
+      <p1 x="500" y="500"/>
+      <p2 x="520" y="500"/>
     </wire>
     <wire>
       <p1 x="520" y="500"/>
       <p2 x="540" y="500"/>
     </wire>
     <wire>
+      <p1 x="560" y="580"/>
+      <p2 x="680" y="580"/>
+    </wire>
+    <wire>
+      <p1 x="520" y="580"/>
+      <p2 x="540" y="580"/>
+    </wire>
+    <wire>
       <p1 x="580" y="520"/>
       <p2 x="600" y="520"/>
     </wire>
     <wire>
+      <p1 x="660" y="520"/>
+      <p2 x="700" y="520"/>
+    </wire>
+    <wire>
+      <p1 x="780" y="540"/>
+      <p2 x="800" y="540"/>
+    </wire>
+    <wire>
       <p1 x="580" y="540"/>
       <p2 x="600" y="540"/>
     </wire>
+    <wire>
+      <p1 x="520" y="500"/>
+      <p2 x="520" y="580"/>
+    </wire>
+    <wire>
+      <p1 x="680" y="560"/>
+      <p2 x="680" y="580"/>
+    </wire>
   </wires>
   <measurementOrdering/>
 </circuit>
\ No newline at end of file
diff --git a/design/alu.dig b/design/alu.dig
index b7b3535..3b66936 100644
--- a/design/alu.dig
+++ b/design/alu.dig
@@ -43,7 +43,7 @@
           <int>4</int>
         </entry>
       </elementAttributes>
-      <pos x="240" y="360"/>
+      <pos x="240" y="280"/>
     </visualElement>
     <visualElement>
       <elementName>Out</elementName>
@@ -57,7 +57,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="580" y="540"/>
+      <pos x="720" y="660"/>
     </visualElement>
     <visualElement>
       <elementName>Out</elementName>
@@ -67,7 +67,7 @@
           <string>Cout</string>
         </entry>
       </elementAttributes>
-      <pos x="580" y="620"/>
+      <pos x="720" y="460"/>
     </visualElement>
     <visualElement>
       <elementName>Out</elementName>
@@ -77,7 +77,7 @@
           <string>Equal</string>
         </entry>
       </elementAttributes>
-      <pos x="580" y="700"/>
+      <pos x="560" y="1660"/>
     </visualElement>
     <visualElement>
       <elementName>equal.dig</elementName>
@@ -100,7 +100,7 @@
           <boolean>true</boolean>
         </entry>
       </elementAttributes>
-      <pos x="440" y="380"/>
+      <pos x="360" y="300"/>
     </visualElement>
     <visualElement>
       <elementName>add8b.dig</elementName>
@@ -118,30 +118,6 @@
       <pos x="380" y="960"/>
     </visualElement>
     <visualElement>
-      <elementName>BitSelector</elementName>
-      <elementAttributes>
-        <entry>
-          <string>Selector Bits</string>
-          <int>3</int>
-        </entry>
-      </elementAttributes>
-      <pos x="520" y="620"/>
-    </visualElement>
-    <visualElement>
-      <elementName>Const</elementName>
-      <elementAttributes>
-        <entry>
-          <string>Value</string>
-          <long>7</long>
-        </entry>
-        <entry>
-          <string>Bits</string>
-          <int>3</int>
-        </entry>
-      </elementAttributes>
-      <pos x="520" y="660"/>
-    </visualElement>
-    <visualElement>
       <elementName>Tunnel</elementName>
       <elementAttributes>
         <entry>
@@ -153,7 +129,7 @@
           <string>R_AplusB</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="380"/>
+      <pos x="340" y="300"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -167,7 +143,7 @@
           <string>R_AminB</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="400"/>
+      <pos x="340" y="320"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -181,7 +157,7 @@
           <string>R_BminA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="420"/>
+      <pos x="340" y="340"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -195,7 +171,7 @@
           <string>R_OnlyA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="460"/>
+      <pos x="340" y="380"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -209,7 +185,7 @@
           <string>R_OnlyB</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="480"/>
+      <pos x="340" y="400"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -223,7 +199,7 @@
           <string>R_MinA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="500"/>
+      <pos x="340" y="420"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -237,7 +213,7 @@
           <string>R_MinB</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="520"/>
+      <pos x="340" y="440"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -251,7 +227,7 @@
           <string>R_ShiftLeftA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="540"/>
+      <pos x="340" y="460"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -265,7 +241,7 @@
           <string>R_ShiftRightA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="560"/>
+      <pos x="340" y="480"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -279,7 +255,7 @@
           <string>R_RotateLeftA</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="580"/>
+      <pos x="340" y="500"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -293,7 +269,7 @@
           <string>R_RotateRight_A</string>
         </entry>
       </elementAttributes>
-      <pos x="420" y="600"/>
+      <pos x="340" y="520"/>
     </visualElement>
     <visualElement>
       <elementName>Tunnel</elementName>
@@ -427,7 +403,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="280" y="660"/>
+      <pos x="200" y="580"/>
     </visualElement>
     <visualElement>
       <elementName>Const</elementName>
@@ -441,7 +417,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="280" y="680"/>
+      <pos x="200" y="600"/>
     </visualElement>
     <visualElement>
       <elementName>sl8b.dig</elementName>
@@ -493,6 +469,64 @@
       </elementAttributes>
       <pos x="360" y="1000"/>
     </visualElement>
+    <visualElement>
+      <elementName>Multiplexer</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Selector Bits</string>
+          <int>4</int>
+        </entry>
+        <entry>
+          <string>flipSelPos</string>
+          <boolean>true</boolean>
+        </entry>
+      </elementAttributes>
+      <pos x="660" y="300"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>NetName</string>
+          <string>C_AplusB</string>
+        </entry>
+      </elementAttributes>
+      <pos x="460" y="780"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>NetName</string>
+          <string>C_AminB</string>
+        </entry>
+      </elementAttributes>
+      <pos x="460" y="880"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Tunnel</elementName>
+      <elementAttributes>
+        <entry>
+          <string>NetName</string>
+          <string>C_BminA</string>
+        </entry>
+      </elementAttributes>
+      <pos x="460" y="980"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Input Splitting</string>
+          <string>8</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>7,1</string>
+        </entry>
+      </elementAttributes>
+      <pos x="420" y="460"/>
+    </visualElement>
   </visualElements>
   <wires>
     <wire>
@@ -508,12 +542,8 @@
       <p2 x="380" y="1280"/>
     </wire>
     <wire>
-      <p1 x="300" y="640"/>
-      <p2 x="440" y="640"/>
-    </wire>
-    <wire>
-      <p1 x="420" y="580"/>
-      <p2 x="440" y="580"/>
+      <p1 x="340" y="320"/>
+      <p2 x="360" y="320"/>
     </wire>
     <wire>
       <p1 x="340" y="1540"/>
@@ -524,24 +554,44 @@
       <p2 x="380" y="900"/>
     </wire>
     <wire>
-      <p1 x="420" y="520"/>
-      <p2 x="440" y="520"/>
+      <p1 x="200" y="580"/>
+      <p2 x="220" y="580"/>
+    </wire>
+    <wire>
+      <p1 x="220" y="580"/>
+      <p2 x="360" y="580"/>
     </wire>
     <wire>
       <p1 x="320" y="1480"/>
       <p2 x="380" y="1480"/>
     </wire>
     <wire>
+      <p1 x="340" y="520"/>
+      <p2 x="360" y="520"/>
+    </wire>
+    <wire>
       <p1 x="240" y="780"/>
       <p2 x="320" y="780"/>
     </wire>
     <wire>
+      <p1 x="440" y="780"/>
+      <p2 x="460" y="780"/>
+    </wire>
+    <wire>
       <p1 x="320" y="780"/>
       <p2 x="380" y="780"/>
     </wire>
     <wire>
-      <p1 x="420" y="460"/>
-      <p2 x="440" y="460"/>
+      <p1 x="340" y="460"/>
+      <p2 x="360" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="400" y="460"/>
+      <p2 x="420" y="460"/>
+    </wire>
+    <wire>
+      <p1 x="700" y="460"/>
+      <p2 x="720" y="460"/>
     </wire>
     <wire>
       <p1 x="320" y="1680"/>
@@ -556,38 +606,46 @@
       <p2 x="460" y="1360"/>
     </wire>
     <wire>
-      <p1 x="420" y="400"/>
-      <p2 x="440" y="400"/>
+      <p1 x="340" y="400"/>
+      <p2 x="360" y="400"/>
     </wire>
     <wire>
       <p1 x="340" y="980"/>
       <p2 x="380" y="980"/>
     </wire>
     <wire>
-      <p1 x="520" y="660"/>
-      <p2 x="540" y="660"/>
+      <p1 x="440" y="980"/>
+      <p2 x="460" y="980"/>
     </wire>
     <wire>
-      <p1 x="280" y="660"/>
-      <p2 x="300" y="660"/>
+      <p1 x="340" y="340"/>
+      <p2 x="360" y="340"/>
     </wire>
     <wire>
-      <p1 x="300" y="660"/>
-      <p2 x="440" y="660"/>
+      <p1 x="420" y="660"/>
+      <p2 x="720" y="660"/>
     </wire>
     <wire>
       <p1 x="340" y="1240"/>
       <p2 x="380" y="1240"/>
     </wire>
     <wire>
-      <p1 x="420" y="600"/>
-      <p2 x="440" y="600"/>
-    </wire>
-    <wire>
       <p1 x="440" y="1560"/>
       <p2 x="460" y="1560"/>
     </wire>
     <wire>
+      <p1 x="200" y="600"/>
+      <p2 x="360" y="600"/>
+    </wire>
+    <wire>
+      <p1 x="240" y="280"/>
+      <p2 x="380" y="280"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="280"/>
+      <p2 x="680" y="280"/>
+    </wire>
+    <wire>
       <p1 x="340" y="860"/>
       <p2 x="380" y="860"/>
     </wire>
@@ -604,16 +662,8 @@
       <p2 x="380" y="1180"/>
     </wire>
     <wire>
-      <p1 x="480" y="540"/>
-      <p2 x="500" y="540"/>
-    </wire>
-    <wire>
-      <p1 x="420" y="540"/>
-      <p2 x="440" y="540"/>
-    </wire>
-    <wire>
-      <p1 x="500" y="540"/>
-      <p2 x="580" y="540"/>
+      <p1 x="220" y="540"/>
+      <p2 x="360" y="540"/>
     </wire>
     <wire>
       <p1 x="440" y="1120"/>
@@ -624,10 +674,6 @@
       <p2 x="380" y="1120"/>
     </wire>
     <wire>
-      <p1 x="420" y="480"/>
-      <p2 x="440" y="480"/>
-    </wire>
-    <wire>
       <p1 x="340" y="1440"/>
       <p2 x="380" y="1440"/>
     </wire>
@@ -636,44 +682,32 @@
       <p2 x="380" y="800"/>
     </wire>
     <wire>
-      <p1 x="240" y="740"/>
-      <p2 x="340" y="740"/>
+      <p1 x="340" y="480"/>
+      <p2 x="360" y="480"/>
     </wire>
     <wire>
-      <p1 x="420" y="420"/>
-      <p2 x="440" y="420"/>
+      <p1 x="240" y="740"/>
+      <p2 x="340" y="740"/>
     </wire>
     <wire>
       <p1 x="320" y="1380"/>
       <p2 x="380" y="1380"/>
     </wire>
     <wire>
-      <p1 x="340" y="1640"/>
-      <p2 x="380" y="1640"/>
+      <p1 x="340" y="420"/>
+      <p2 x="360" y="420"/>
     </wire>
     <wire>
-      <p1 x="280" y="680"/>
-      <p2 x="440" y="680"/>
+      <p1 x="340" y="1640"/>
+      <p2 x="380" y="1640"/>
     </wire>
     <wire>
       <p1 x="360" y="1000"/>
       <p2 x="380" y="1000"/>
     </wire>
     <wire>
-      <p1 x="240" y="360"/>
-      <p2 x="460" y="360"/>
-    </wire>
-    <wire>
-      <p1 x="560" y="620"/>
-      <p2 x="580" y="620"/>
-    </wire>
-    <wire>
-      <p1 x="500" y="620"/>
-      <p2 x="520" y="620"/>
-    </wire>
-    <wire>
-      <p1 x="300" y="620"/>
-      <p2 x="440" y="620"/>
+      <p1 x="220" y="360"/>
+      <p2 x="360" y="360"/>
     </wire>
     <wire>
       <p1 x="440" y="1260"/>
@@ -684,22 +718,34 @@
       <p2 x="380" y="1580"/>
     </wire>
     <wire>
-      <p1 x="420" y="560"/>
-      <p2 x="440" y="560"/>
+      <p1 x="340" y="300"/>
+      <p2 x="360" y="300"/>
+    </wire>
+    <wire>
+      <p1 x="220" y="560"/>
+      <p2 x="360" y="560"/>
     </wire>
     <wire>
       <p1 x="320" y="880"/>
       <p2 x="380" y="880"/>
     </wire>
     <wire>
-      <p1 x="420" y="500"/>
-      <p2 x="440" y="500"/>
+      <p1 x="440" y="880"/>
+      <p2 x="460" y="880"/>
+    </wire>
+    <wire>
+      <p1 x="340" y="500"/>
+      <p2 x="360" y="500"/>
     </wire>
     <wire>
       <p1 x="440" y="1460"/>
       <p2 x="460" y="1460"/>
     </wire>
     <wire>
+      <p1 x="340" y="440"/>
+      <p2 x="360" y="440"/>
+    </wire>
+    <wire>
       <p1 x="340" y="760"/>
       <p2 x="380" y="760"/>
     </wire>
@@ -712,26 +758,18 @@
       <p2 x="460" y="1080"/>
     </wire>
     <wire>
-      <p1 x="300" y="440"/>
-      <p2 x="440" y="440"/>
+      <p1 x="440" y="1660"/>
+      <p2 x="560" y="1660"/>
     </wire>
     <wire>
-      <p1 x="420" y="380"/>
-      <p2 x="440" y="380"/>
+      <p1 x="340" y="380"/>
+      <p2 x="360" y="380"/>
     </wire>
     <wire>
       <p1 x="340" y="1340"/>
       <p2 x="380" y="1340"/>
     </wire>
     <wire>
-      <p1 x="540" y="700"/>
-      <p2 x="580" y="700"/>
-    </wire>
-    <wire>
-      <p1 x="440" y="1660"/>
-      <p2 x="540" y="1660"/>
-    </wire>
-    <wire>
       <p1 x="320" y="780"/>
       <p2 x="320" y="880"/>
     </wire>
@@ -808,32 +846,28 @@
       <p2 x="340" y="1540"/>
     </wire>
     <wire>
-      <p1 x="500" y="540"/>
-      <p2 x="500" y="620"/>
-    </wire>
-    <wire>
-      <p1 x="540" y="700"/>
-      <p2 x="540" y="1660"/>
+      <p1 x="420" y="460"/>
+      <p2 x="420" y="660"/>
     </wire>
     <wire>
-      <p1 x="540" y="640"/>
-      <p2 x="540" y="660"/>
+      <p1 x="680" y="280"/>
+      <p2 x="680" y="300"/>
     </wire>
     <wire>
-      <p1 x="300" y="440"/>
-      <p2 x="300" y="620"/>
+      <p1 x="220" y="360"/>
+      <p2 x="220" y="540"/>
     </wire>
     <wire>
-      <p1 x="300" y="620"/>
-      <p2 x="300" y="640"/>
+      <p1 x="220" y="540"/>
+      <p2 x="220" y="560"/>
     </wire>
     <wire>
-      <p1 x="300" y="640"/>
-      <p2 x="300" y="660"/>
+      <p1 x="220" y="560"/>
+      <p2 x="220" y="580"/>
     </wire>
     <wire>
-      <p1 x="460" y="360"/>
-      <p2 x="460" y="380"/>
+      <p1 x="380" y="280"/>
+      <p2 x="380" y="300"/>
     </wire>
   </wires>
   <measurementOrdering/>
diff --git a/design/min8b.dig b/design/min8b.dig
index c729da5..e4b5f08 100644
--- a/design/min8b.dig
+++ b/design/min8b.dig
@@ -15,7 +15,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="500" y="300"/>
+      <pos x="300" y="320"/>
     </visualElement>
     <visualElement>
       <elementName>In</elementName>
@@ -29,21 +29,7 @@
           <int>8</int>
         </entry>
       </elementAttributes>
-      <pos x="500" y="340"/>
-    </visualElement>
-    <visualElement>
-      <elementName>Out</elementName>
-      <elementAttributes>
-        <entry>
-          <string>Label</string>
-          <string>X</string>
-        </entry>
-        <entry>
-          <string>Bits</string>
-          <int>8</int>
-        </entry>
-      </elementAttributes>
-      <pos x="700" y="320"/>
+      <pos x="300" y="360"/>
     </visualElement>
     <visualElement>
       <elementName>In</elementName>
@@ -53,7 +39,7 @@
           <string>Cin</string>
         </entry>
       </elementAttributes>
-      <pos x="500" y="400"/>
+      <pos x="300" y="420"/>
     </visualElement>
     <visualElement>
       <elementName>Out</elementName>
@@ -63,67 +49,136 @@
           <string>Cout</string>
         </entry>
       </elementAttributes>
-      <pos x="700" y="360"/>
+      <pos x="580" y="440"/>
     </visualElement>
     <visualElement>
       <elementName>2c.dig</elementName>
       <elementAttributes/>
-      <pos x="520" y="340"/>
+      <pos x="320" y="360"/>
     </visualElement>
     <visualElement>
       <elementName>add8b.dig</elementName>
       <elementAttributes/>
-      <pos x="600" y="320"/>
+      <pos x="480" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>add1b.dig</elementName>
+      <elementAttributes/>
+      <pos x="480" y="440"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>splitterSpreading</string>
+          <int>5</int>
+        </entry>
+        <entry>
+          <string>Input Splitting</string>
+          <string>8</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>0-7,7-7</string>
+        </entry>
+      </elementAttributes>
+      <pos x="440" y="340"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>X</string>
+        </entry>
+        <entry>
+          <string>Bits</string>
+          <int>8</int>
+        </entry>
+      </elementAttributes>
+      <pos x="580" y="340"/>
     </visualElement>
   </visualElements>
   <wires>
     <wire>
-      <p1 x="520" y="320"/>
-      <p2 x="600" y="320"/>
+      <p1 x="300" y="320"/>
+      <p2 x="420" y="320"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="480"/>
+      <p2 x="480" y="480"/>
+    </wire>
+    <wire>
+      <p1 x="460" y="340"/>
+      <p2 x="480" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="420" y="340"/>
+      <p2 x="440" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="540" y="340"/>
+      <p2 x="580" y="340"/>
+    </wire>
+    <wire>
+      <p1 x="300" y="420"/>
+      <p2 x="420" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="440" y="420"/>
+      <p2 x="560" y="420"/>
+    </wire>
+    <wire>
+      <p1 x="300" y="360"/>
+      <p2 x="320" y="360"/>
+    </wire>
+    <wire>
+      <p1 x="380" y="360"/>
+      <p2 x="480" y="360"/>
     </wire>
     <wire>
-      <p1 x="660" y="320"/>
-      <p2 x="700" y="320"/>
+      <p1 x="540" y="360"/>
+      <p2 x="560" y="360"/>
     </wire>
     <wire>
-      <p1 x="500" y="400"/>
-      <p2 x="520" y="400"/>
+      <p1 x="460" y="440"/>
+      <p2 x="480" y="440"/>
     </wire>
     <wire>
-      <p1 x="500" y="340"/>
-      <p2 x="520" y="340"/>
+      <p1 x="540" y="440"/>
+      <p2 x="580" y="440"/>
     </wire>
     <wire>
-      <p1 x="580" y="340"/>
-      <p2 x="600" y="340"/>
+      <p1 x="400" y="460"/>
+      <p2 x="480" y="460"/>
     </wire>
     <wire>
-      <p1 x="660" y="340"/>
-      <p2 x="680" y="340"/>
+      <p1 x="420" y="380"/>
+      <p2 x="480" y="380"/>
     </wire>
     <wire>
-      <p1 x="520" y="360"/>
-      <p2 x="600" y="360"/>
+      <p1 x="380" y="380"/>
+      <p2 x="400" y="380"/>
     </wire>
     <wire>
-      <p1 x="680" y="360"/>
-      <p2 x="700" y="360"/>
+      <p1 x="400" y="380"/>
+      <p2 x="400" y="460"/>
     </wire>
     <wire>
-      <p1 x="500" y="300"/>
-      <p2 x="520" y="300"/>
+      <p1 x="560" y="360"/>
+      <p2 x="560" y="420"/>
     </wire>
     <wire>
-      <p1 x="520" y="300"/>
-      <p2 x="520" y="320"/>
+      <p1 x="420" y="380"/>
+      <p2 x="420" y="420"/>
     </wire>
     <wire>
-      <p1 x="520" y="360"/>
-      <p2 x="520" y="400"/>
+      <p1 x="420" y="320"/>
+      <p2 x="420" y="340"/>
     </wire>
     <wire>
-      <p1 x="680" y="340"/>
-      <p2 x="680" y="360"/>
+      <p1 x="440" y="420"/>
+      <p2 x="440" y="480"/>
     </wire>
   </wires>
   <measurementOrdering/>
diff --git a/src/alu.vhd b/src/alu.vhd
index 0022b4e..7da5696 100644
--- a/src/alu.vhd
+++ b/src/alu.vhd
@@ -25,7 +25,8 @@ architecture Behavioral of ALU is
 				 R_RotateRightA,
 				 R_AllZeros,
 				 R_AllOnes,
-				 R: std_logic_vector(7 downto 0);
+				 R: std_logic_vector(7 downto 0) := (others => '0');
+	signal C_AMinB, C_BMinA, C_MinA, C_MinB: std_logic := '0'; -- Minus carry out (test bench edge case)
 	component add8b is
 		port (
 			A: in std_logic_vector(7 downto 0);
@@ -45,7 +46,8 @@ architecture Behavioral of ALU is
 	component twoc is
 		port (
 			A: in std_logic_vector(7 downto 0);
-			X: out std_logic_vector(7 downto 0));
+			X: out std_logic_vector(7 downto 0);
+      Cout: out std_logic);
 	end component;
 	component sl8b is
 		port (
@@ -91,65 +93,82 @@ begin
 			B => B,
 			Cin => '0',
 			X => R_AminB,
-			Cout => open);
+			Cout => C_AMinB);
 	BminA: component min8b
 		port map(
 			A => B,
 			B => A,
 			Cin => '0',
 			X => R_BminA,
-			Cout => open);
+			Cout => C_BMinA);
 	R_OnlyA <= A;
 	R_OnlyB <= B;
 	MinA: component twoc
-		port map(A => A, X => R_MinA);
+		port map(
+      A => A,
+      X => R_MinA,
+      Cout => C_MinA);
 	MinB: component twoc
-		port map(A => B, X => R_MinA);
+		port map(
+      A => B,
+      X => R_MinB,
+      Cout => C_MinB);
 	ShiftLeftA: component sl8b
 		port map(
 			A => A,
-			S => B,
+			S => x"01",
 			X => R_ShiftLeftA);
 	ShiftRightA: component sr8b
 		port map(
 			A => A,
-			S => B,
+			S => x"01",
 			X => R_ShiftRightA);
 	RotateLeftA: component rl8b
 		port map(
 			A => A,
-			S => B,
+			S => x"01",
 			X => R_RotateLeftA);
 	RotateRightA: component rr8b
 		port map(
 			A => A,
-			S => B,
+			S => x"01",
 			X => R_RotateRightA);
 
 	with Op select
 		R <=
-			R_AplusB       when x"0",
-			R_AminB        when x"1",
-			R_BminA        when x"2",
-			R_Dummy        when x"3",
-			R_OnlyA        when x"4",
-			R_OnlyB        when x"5",
-			R_MinA         when x"6",
-			R_MinB         when x"7",
-			R_ShiftLeftA   when x"8",
-			R_ShiftRightA  when x"9",
-			R_RotateLeftA  when x"a",
-			R_RotateRightA when x"b",
-			R_Dummy        when x"c",
-			R_Dummy        when x"d",
-			R_AllZeros     when x"e",
-			R_AllOnes      when x"f",
+			R_AplusB       when x"0", -- AplusB
+			R_AminB        when x"1", -- AminB
+			R_BminA        when x"2", -- BminA
+			R_Dummy        when x"3", -- Dummy
+			R_OnlyA        when x"4", -- OnlyA
+			R_OnlyB        when x"5", -- OnlyB
+			R_MinA         when x"6", -- MinA
+			R_MinB         when x"7", -- MinB
+			R_ShiftLeftA   when x"8", -- ShiftLeftA
+			R_ShiftRightA  when x"9", -- ShiftRightA
+			R_RotateLeftA  when x"a", -- RotateLeftA
+			R_RotateRightA when x"b", -- RotateRightA
+			R_Dummy        when x"c", -- Dummy
+			R_Dummy        when x"d", -- Dummy
+			R_AllZeros     when x"e", -- AllZeros
+			R_AllOnes      when x"f", -- AllOnes
 			(others => '0') when others;
+	with Op select
+		Cout <=
+			R(7) when x"0" | x"3" | x"c" | x"d", -- AplusB, MinA, MinB, Dummy
+			C_AMinB when x"1", -- AminB
+			C_BMinA when x"2", -- BminA
+			A(7) when x"4" | x"8" | x"a", -- OnlyA, ShiftLeftA, RotateLeftA
+			B(7) when x"5", -- OnlyB
+      C_MinA when x"6", -- MinA TODO FIX
+      C_MinB when x"7", -- MinB TODO FIX
+			'0'  when x"9" | x"b" | x"e", -- ShiftRightA, RotateRightA, AllZeros
+			'1'  when x"f", -- AllOnes
+			'0' when others;
 	eq: component eq8b
 		port map(
 			A => A,
 			B => B,
 			Equal => Equal);
 	Res <= R;
-	Cout <= R(7);
 end Behavioral;
diff --git a/src/eq8b.vhd b/src/eq8b.vhd
index 0c382a8..1f929e5 100644
--- a/src/eq8b.vhd
+++ b/src/eq8b.vhd
@@ -4,8 +4,7 @@ USE ieee.numeric_std.all;
 
 entity eq8b is
 	port (
-		A: in std_logic_vector(7 downto 0);
-		B: in std_logic_vector(7 downto 0);
+		A, B: in std_logic_vector(7 downto 0);
 		Equal: out std_logic);
 end eq8b;
 
diff --git a/src/min8b.vhd b/src/min8b.vhd
index f2623aa..898d3c7 100644
--- a/src/min8b.vhd
+++ b/src/min8b.vhd
@@ -4,8 +4,7 @@ USE ieee.numeric_std.all;
 
 entity min8b is
 	port (
-		A: in std_logic_vector(7 downto 0);
-		B: in std_logic_vector(7 downto 0);
+		A, B: in std_logic_vector(7 downto 0);
 		Cin: in std_logic;
 		X: out std_logic_vector(7 downto 0);
 		Cout: out std_logic);
@@ -13,29 +12,44 @@ end min8b;
 
 architecture Behavioral of min8b is
 	signal Bmin: std_logic_vector(7 downto 0);
+  signal Bcom: std_logic;
+  signal carry: std_logic;
 	component twoc
 		port (
 			A: in std_logic_vector(7 downto 0);
-			X: out std_logic_vector(7 downto 0));
+			X: out std_logic_vector(7 downto 0);
+      Cout: out std_logic);
 	end component;
 	component add8b
 		port (
-			A: in std_logic_vector(7 downto 0);
-			B: in std_logic_vector(7 downto 0);
+			A, B: in std_logic_vector(7 downto 0);
 			Cin: in std_logic;
 			X: out std_logic_vector(7 downto 0);
 			Cout: out std_logic);
 	end component;
+	component add1b
+		port (
+			A, B, Cin: in std_logic;
+			X, Cout: out std_logic);
+	end component;
 begin
 	complement: component twoc
 		port map (
 			A => B,
-			X => Bmin);
-	add: component add8b
+			X => Bmin,
+      Cout => Bcom);
+	add8: component add8b
 		port map (
 			A => A,
 			B => Bmin,
 			Cin => Cin,
 			X => X,
-			Cout => Cout);
+			Cout => carry);
+  add1: component add1b
+    port map(
+      A => A(7),
+      B => Bcom,
+      Cin => carry,
+      X => Cout,
+      Cout => open);
 end Behavioral;
diff --git a/src/min8b_tb.vhd b/src/min8b_tb.vhd
new file mode 100644
index 0000000..fb22cb0
--- /dev/null
+++ b/src/min8b_tb.vhd
@@ -0,0 +1,51 @@
+library ieee;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+
+entity min8b_tb is
+end min8b_tb;
+
+architecture behavioral of min8b_tb is
+	component min8b
+		port (
+			A: in std_logic_vector(7 downto 0);
+			B: in std_logic_vector(7 downto 0);
+			Cin: in std_logic;
+			X: out std_logic_vector(7 downto 0);
+			Cout: out std_logic);
+	end component;
+	signal A: std_logic_vector(7 downto 0);
+	signal B: std_logic_vector(7 downto 0);
+	signal Cin: std_logic;
+	signal test_case: std_logic_vector(7 downto 0) := (others => '0');
+	signal Cout: std_logic;
+	signal OK: boolean := true;
+begin
+	UUT: component twoc
+		port map(
+			A => A,
+			X => X);
+
+	tb: process
+		variable temp: std_logic_vector(8 downto 0);
+	begin
+		Cin <= '0';
+		for i in 0 to 255 loop
+			test_case <= std_logic_vector(to_unsigned(i,8));
+			wait for 1 ps;
+			A <= test_case;
+
+			X_t := -i;
+
+			wait for 5 ns;
+			if to_signed(X_t, 8) /= signed(X) then
+				OK <= false;
+			end if;
+			wait for 5 ns;
+		end loop;
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/src/twoc.vhd b/src/twoc.vhd
index 5c86056..7a2c89d 100644
--- a/src/twoc.vhd
+++ b/src/twoc.vhd
@@ -5,11 +5,13 @@ USE ieee.numeric_std.all;
 entity twoc is
 	port (
 		A: in std_logic_vector(7 downto 0);
-		X: out std_logic_vector(7 downto 0));
+		X: out std_logic_vector(7 downto 0);
+    Cout: out std_logic);
 end twoc;
 
 architecture Behavioral of twoc is
 	signal NA: std_logic_vector(7 downto 0); -- not A
+	signal A0: std_logic; -- A = 0
 	component add8b is
 		port (
 			A: in std_logic_vector(7 downto 0);
@@ -23,7 +25,9 @@ begin
 	add: component add8b -- add one
 		port map (
 			A => NA,
-			B => "00000001",
+			B => x"01",
 			Cin => '0',
-			X => X);
+			X => X,
+      Cout => A0);
+  Cout <= not (A0 or A(7));
 end Behavioral;
diff --git a/src/twoc_tb.vhd b/src/twoc_tb.vhd
new file mode 100644
index 0000000..fc53bea
--- /dev/null
+++ b/src/twoc_tb.vhd
@@ -0,0 +1,46 @@
+library ieee;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+
+entity twoc_tb is
+end twoc_tb;
+
+architecture behavioral of twoc_tb is
+	component twoc
+		port (
+			A: in std_logic_vector(7 downto 0);
+			X: out std_logic_vector(7 downto 0));
+	end component;
+	signal A: std_logic_vector(7 downto 0);
+	signal X: std_logic_vector(7 downto 0);
+	signal test_case: std_logic_vector(7 downto 0) := (others => '0');
+	signal OK: boolean := true;
+begin
+	UUT: component twoc
+		port map(
+			A => A,
+			X => X);
+
+	tb: process
+		variable X_t: integer;
+
+	begin
+		for i in 0 to 255 loop
+			test_case <= std_logic_vector(to_unsigned(i,8));
+			wait for 1 ps;
+			A <= test_case;
+
+			X_t := -i;
+
+			wait for 5 ns;
+			if to_signed(X_t, 8) /= signed(X) then
+				OK <= false;
+			end if;
+			wait for 5 ns;
+		end loop;
+		wait; -- stop for simulator
+	end process;
+end;