diff --git a/Circuit.cpp b/Circuit.cpp
index 497bb09..e264748 100644
--- a/Circuit.cpp
+++ b/Circuit.cpp
@@ -64,10 +64,10 @@ bool Circuit::getValue() {
     }
     /* otherwise, this test: */
     for (auto s : this->segs) {
-        if (s->pullup) {
+        if (s->pull == Pull::UP) {
             return true;
         }
-        if (s->pulldown) {
+        if (s->pull == Pull::DOWN) {
             return false;
         }
         if (s->on) {
diff --git a/Cpu6502.cpp b/Cpu6502.cpp
index b8c29d6..cc70829 100644
--- a/Cpu6502.cpp
+++ b/Cpu6502.cpp
@@ -18,7 +18,7 @@
 
 
 #define TRACEREG 1
-//#define TRACESEG 1
+#define TRACESEG 1
 
 
 
diff --git a/Makefile b/Makefile
index 3c0dd80..1f594e0 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ v6502: $(OBJS)
 
 
 clean:
-	-rm -f v6502 v6502.exe $(OBJS) $(DEPS)
+	-rm -Rf v6502 v6502.exe $(OBJS) $(DEPS) doxygen
 
 
 
diff --git a/Trace.cpp b/Trace.cpp
index d78d58a..263186a 100644
--- a/Trace.cpp
+++ b/Trace.cpp
@@ -27,10 +27,9 @@ static void pHexw(const unsigned short x) {
 void Trace::dumpSegments() const {
     for (auto sp : this->s) {
         Segment* seg = sp.second.get();
-        assert(!(seg->pullup && seg->pulldown));
-        if (seg->pullup) {
+        if (seg->pull == Pull::UP) {
             std::cout << (seg->on ? "U" : "u");
-        } else if (seg->pulldown) {
+        } else if (seg->pull == Pull::DOWN) {
             std::cout << (seg->on ? "D" : "d");
         } else {
             std::cout << (seg->on ? "F" : "f");
diff --git a/trans.h b/trans.h
index 893a79a..4d7c896 100644
--- a/trans.h
+++ b/trans.h
@@ -8,33 +8,46 @@
 #ifndef TRANS_H
 #define	TRANS_H
 
-#include <string>
-#include <set>
 #include "ptr_less.h"
+#include <set>
+#include <string>
+
+
 
 class Trans;
 
+enum class Pull { UP, DOWN, FLOAT };
+
 class Segment {
 public:
-    std::string id;
+
+    const std::string id;
     std::set<Trans*> gates;
     std::set<Trans*> c1c2s;
-
-    bool on;
-    bool pulldown;
-    bool pullup;
-
     bool vss;
     bool vcc;
 
-    Segment(const std::string& id) : id(id), on(false), pulldown(false), pullup(id[0] == '+'), vss(false), vcc(false) {
+    Pull pull;
+    bool on;
+
+
+
+    Segment(const std::string& id) : id(id), vss(false), vcc(false), pull(id[0]=='+' ? Pull::UP : Pull::FLOAT), on(false) {
     }
 
-    void set(bool up) {
-        this->pullup = up;
-        this->pulldown = !up;
+    virtual ~Segment() {
     }
 
+
+
+    void set(const bool up) {
+        this->pull = (up ? Pull::UP : Pull::DOWN);
+    }
+
+    bool operator<(const Segment& that) { return this->id < that.id; }
+
+
+
     static unsigned char asByte(Segment* b7, Segment* b6, Segment* b5, Segment* b4, Segment* b3, Segment* b2, Segment* b1, Segment* b0) {
         return b7->on << 0x7 | b6->on << 0x6 | b5->on << 0x5 | b4->on << 0x4 | b3->on << 0x3 | b2->on << 0x2 | b1->on << 0x1 | b0->on;
     }
@@ -43,22 +56,30 @@ public:
         return bf->on << 0xf | be->on << 0xe | bd->on << 0xd | bc->on << 0xc | bb->on << 0xb | ba->on << 0xa | b9->on << 0x9 | b8->on << 0x8 | b7->on << 0x7 | b6->on << 0x6 | b5->on << 0x5 | b4->on << 0x4 | b3->on << 0x3 | b2->on << 0x2 | b1->on << 0x1 | b0->on;
     }
 
-    bool operator<(const Segment& that) { return this->id < that.id; }
+private:
+
+    Segment(const Segment&) = delete;
+    Segment& operator=(const Segment&) = delete;
 };
 
 typedef std::set<Segment*,ptr_less<Segment>> setpSeg;
 
+
+
+
+
+
 class Trans {
 public:
+
     Segment* c1;
-    Segment* gate;
     Segment* c2;
 
     bool on;
 
-public:
 
-    Trans(Segment* c1, Segment* gate, Segment* c2) : c1(c1), gate(gate), c2(c2), on(false) {
+
+    Trans(Segment* c1, Segment* gate, Segment* c2) : c1(c1), c2(c2), on(false) {
         c1->c1c2s.insert(this);
         gate->gates.insert(this);
         c2->c1c2s.insert(this);
@@ -68,8 +89,9 @@ public:
     }
 
 private:
-    Trans(const Trans&);
-    Trans& operator=(const Trans&);
+
+    Trans(const Trans&) = delete;
+    Trans& operator=(const Trans&) = delete;
 };
 
 #endif	/* TRANS_H */