diff --git a/Kernel.cpp b/Kernel.cpp
index 91b5000..7d5e9e7 100644
--- a/Kernel.cpp
+++ b/Kernel.cpp
@@ -1,19 +1,29 @@
 #include "Kernel.h"
 
-Kernel::Kernel(const List<PhysicalPage> &free_pages, const List<PhysicalPage> &busy_pages)
-: free_pages(free_pages), busy_pages(busy_pages) {
-}
+using std::next;
 
+Kernel::Kernel(const List<PhysicalPage> &free_pages, const List<PhysicalPage> &busy_pages)
+: free_pages(free_pages), busy_pages(busy_pages), swapped_page(nullptr) {}
 
 void Kernel::page_fault(PageTable page_table, const int idx) {
-    PhysicalPage *page;
+    PhysicalPage *page = nullptr;
     if (!this->free_pages.is_empty()) {
-        page = free_pages.last();
+        page = free_pages.get_head()->prev;
         free_pages.remove(page);
         busy_pages.insert_tail(page);
     } else {
-        page = nullptr; // TODO: page replacement algorithm
+        for (PhysicalPage *curr = busy_pages.get_head();; curr = curr->next) {
+            if ((*curr->PT)[curr->idx].R)
+                (*curr->PT)[curr->idx].R = false;
+            else {
+                curr->PT->entries.erase(next(curr->PT->entries.begin(), curr->idx));
+                page = curr;
+                busy_pages.set_head(curr->next);
+                break;
+            }
+        }
     }
+
     if (page) {
         page_table[idx].PPN = page->PPN;
         page_table[idx].P = true;
@@ -23,7 +33,10 @@ void Kernel::page_fault(PageTable page_table, const int idx) {
 }
 
 void Kernel::stat_update() {
-    for (int i = 0; i < 10; ++i) {
-        // TODO: update busy page stats
+    int i;
+    PhysicalPage *curr;
+    for (i = 0, curr = busy_pages.get_head(); i < 10; ++i, curr = curr->next) {
+        if ((*curr->PT)[curr->idx].R)
+            (*curr->PT)[curr->idx].R = false;
     }
 }
diff --git a/Kernel.h b/Kernel.h
index 8eb63ee..7ae025a 100644
--- a/Kernel.h
+++ b/Kernel.h
@@ -11,7 +11,7 @@
 class Kernel {
 public:
         List<PhysicalPage> free_pages, busy_pages;
-        // TODO: RunQ
+        PhysicalPage *swapped_page;
         std::vector<Process> RunQ;
         Kernel(const List<PhysicalPage> &free_pages, const List<PhysicalPage> &busy_pages);
         void page_fault(PageTable page_table, int idx);
diff --git a/List.h b/List.h
index e9c11fa..8eff143 100644
--- a/List.h
+++ b/List.h
@@ -3,96 +3,84 @@
 
 template<typename T>
 class List {
-    T *head, *tail;
+    T *head;
     unsigned int num;
-    const unsigned int idx;
-    public:
-        explicit List(unsigned int idx);
-        T *first();
-        T *last();
-        void insert_head(T *elem);
-        void insert_tail(T *elem);
-        void insert_before(T *elem1, T *elem2);
-        void remove(T *elem);
-        bool is_empty();
-        [[nodiscard]] unsigned int get_num() const;
+public:
+    explicit List();
+    [[nodiscard]] T *get_head();
+    void set_head(T *head);
+    void insert_head(T *elem);
+    void insert_tail(T *elem);
+    void insert_before(T *elem, T *reference_point);
+    void remove(T *elem);
+    bool is_empty();
+    [[nodiscard]] unsigned int get_num() const;
 };
 
-#define for_each_in_list(elem, list)    \
-    for (                               \
-        (elem) = (list)->first();       \
-        (elem) != nullptr;              \
-        (elem) = (list)->next(elem)     \
-    )
-
 template<typename T>
-List<T>::List(const unsigned int idx) : head{nullptr}, tail{nullptr}, num{0}, idx{idx} {
+List<T>::List() : head{nullptr}, num{0} {
 }
 
 template<typename T>
-T * List<T>::first() {
-    return this->head;
+T *List<T>::get_head() {
+    return head;
 }
 
 template<typename T>
-T * List<T>::last() {
-    return this->tail;
+void List<T>::set_head(T *head) {
+    this->head = head;
 }
 
+
 template<typename T>
 void List<T>::insert_head(T *elem) {
-    const unsigned int idx{this->idx};
+    if (!head)
+        elem->next = elem->prev = elem;
+
+    else {
+        elem->next = head;
+        elem->prev = head->prev;
+        head->prev->next = elem;
+        head->prev = elem;
+    }
 
-    elem->next[idx] = this->head;
-    elem->prev[idx] = nullptr;
-    if (this->head != nullptr)
-        this->head->prev[idx] = elem;
-    if (this->tail == nullptr)
-        this->tail = elem;
     this->head = elem;
     ++this->num;
 }
 
 template<typename T>
 void List<T>::insert_tail(T *elem) {
-    const unsigned int idx{this->idx};
-
-    elem->next[idx] = nullptr;
-    elem->prev[idx] = this->tail;
-    if (this->tail != nullptr)
-        this->tail->next[idx] = elem;
-    if (this->head == nullptr)
-        this->head = elem;
-    this->tail = elem;
+    if (!head)
+        elem->next = elem->prev = elem;
+    else {
+        elem->next = head;
+        elem->prev = head->prev;
+        head->prev->next = elem;
+        head->prev = elem;
+    }
     ++this->num;
 }
 
 template<typename T>
-void List<T>::insert_before(T *elem1, T *elem2) {
-    const unsigned int idx{this->idx};
-
-    elem1->next[idx] = elem2;
-    elem1->prev[idx] = elem2->prev[idx];
-    elem2->prev[idx] = elem1;
-    if (elem1->prev[idx] == nullptr)
-        this->head = elem1;
+void List<T>::insert_before(T *elem, T *reference_point) {
+    elem->next = reference_point;
+    elem->prev = reference_point->prev;
+    reference_point->prev = elem;
+    if (elem->prev == nullptr)
+        this->head = elem;
     else
-        elem1->prev[idx]->next[idx] = elem1;
+        elem->prev->next = elem;
     ++this->num;
 }
 
 template<typename T>
 void List<T>::remove(T *elem) {
-    const unsigned int idx{this->idx};
-
-    if (elem->next[idx] != nullptr)
-        elem->next[idx]->prev[idx] = elem->prev[idx];
-    if (elem->prev[idx] != nullptr)
-        elem->prev[idx]->next[idx] = elem->next[idx];
+    if (elem->next)
+        elem->next->prev = elem->prev;
+    if (elem->prev)
+        elem->prev->next = elem->next;
     if (this->head == elem)
-        this->head = elem->next[idx];
-    if (this->tail == elem)
-        this->tail = elem->prev[idx];
+        this->head = elem->next;
     --this->num;
 }
 
diff --git a/MMU.h b/MMU.h
index b389a92..938b3ed 100644
--- a/MMU.h
+++ b/MMU.h
@@ -12,7 +12,6 @@ enum AccessType {
 class MMU {
     public:
         static void access(Kernel kernel, PageTable table, int index, AccessType type);
-        // TODO type of access
 };
 
 
diff --git a/PageTable.cpp b/PageTable.cpp
index 84789a1..4e07828 100644
--- a/PageTable.cpp
+++ b/PageTable.cpp
@@ -1,5 +1,5 @@
 #include "PageTable.h"
 
-PTE & PageTable::operator[](const int index) {
+PTE &PageTable::operator[](const unsigned int index) {
     return this->entries.at(index);
 }
diff --git a/PageTable.h b/PageTable.h
index f6293fd..691d506 100644
--- a/PageTable.h
+++ b/PageTable.h
@@ -1,7 +1,3 @@
-//
-// Created by rhinemann on 10.03.25.
-//
-
 #ifndef PAGETABLE_H
 #define PAGETABLE_H
 
@@ -12,7 +8,7 @@
 class PageTable {
     public:
         std::vector<PTE> entries;
-        PTE &operator[](int index);
+        PTE &operator[](unsigned int index);
 };
 
 #endif //PAGETABLE_H
diff --git a/PhysicalPage.cpp b/PhysicalPage.cpp
index 1f576dc..a1e09d1 100644
--- a/PhysicalPage.cpp
+++ b/PhysicalPage.cpp
@@ -1,6 +1,7 @@
 #include "PhysicalPage.h"
 
-PhysicalPage::PhysicalPage(const unsigned int PPN): PPN(PPN) {
+PhysicalPage::PhysicalPage(const unsigned int PPN)
+: PPN(PPN), idx(0), PT{nullptr}, next{nullptr}, prev(nullptr) {
 }
 
 void PhysicalPage::take_up(PageTable *PT, const unsigned int idx) {
diff --git a/PhysicalPage.h b/PhysicalPage.h
index bf06c0b..2c4935a 100644
--- a/PhysicalPage.h
+++ b/PhysicalPage.h
@@ -1,7 +1,3 @@
-//
-// Created by rhinemann on 10.03.25.
-//
-
 #ifndef PHYSICALPAGE_H
 #define PHYSICALPAGE_H
 
@@ -11,7 +7,7 @@ class PhysicalPage {
     public:
         unsigned int PPN, idx;
         PageTable *PT;
-        PhysicalPage *next[2], *prev[2];
+        PhysicalPage *next, *prev;
 
         explicit PhysicalPage(unsigned int PPN);
 
diff --git a/Process.cpp b/Process.cpp
index e20e0d5..991f895 100644
--- a/Process.cpp
+++ b/Process.cpp
@@ -4,6 +4,6 @@ Process::Process(PageTable *pageTable, const unsigned int executionTime)
 : pageTable(pageTable), executionTime(executionTime), elapsedTime(0) {
 }
 
-bool Process::is_finished() {
+bool Process::is_finished() const {
     return elapsedTime >= executionTime;
 }
diff --git a/Process.h b/Process.h
index 74f6f1b..da575ce 100644
--- a/Process.h
+++ b/Process.h
@@ -8,7 +8,7 @@ class Process {
         PageTable *pageTable;
         unsigned int executionTime, elapsedTime;
         Process(PageTable *pageTable, unsigned int executionTime);
-        bool is_finished();
+        [[nodiscard]] bool is_finished() const;
 };
 
 
diff --git a/main.cpp b/main.cpp
index a3a0b92..1f08d03 100644
--- a/main.cpp
+++ b/main.cpp
@@ -11,7 +11,7 @@ int main() {
     std::mt19937 gen(rd());
     std::uniform_int_distribution<unsigned int> distribution(0, 10);
 
-    List<PhysicalPage> free_pages(0), busy_pages(0);
+    List<PhysicalPage> free_pages, busy_pages;
     Kernel kernel(free_pages, busy_pages);
 
     for (int i = 0; i < PAGE_N; ++i) {
@@ -22,10 +22,14 @@ int main() {
         kernel.RunQ.emplace_back(nullptr, distribution(gen));
     }
 
+    while (!kernel.RunQ.empty()) {
+
+    }
+
     for (const auto process : kernel.RunQ)
         std::cout << process.executionTime << std::endl;
 
-    // std::cout << MAX_PROC << std::endl;
+    std::cout << MAX_PROC << std::endl;
 
     return 0;
 }