diff --git a/Makefile b/Makefile
index f4ec520..6d006f6 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,7 @@ CPPFLAGS += $(foreach dir, $(SUBDIRS), -I$(dir))
 asmsrc=$(wildcard *.asm)
 asmobj=$(asmsrc:%.asm=%.o)
 csrc=$(shell find $(SUBDIRS) -type f -name "*.c")#   $(wildcard *.c)
-cobj=$(csrc:%.c=%.o) core/cpu_context_switch.o
+cobj=$(csrc:%.c=%.o) core/cpu_context_switch.o core/irq_pit.o
 deps = $(csrc:%.c=%.d)
 
 kernel:$(asmobj) $(cobj) linker.ld
diff --git a/core/cpu_context_switch.S b/core/cpu_context_switch.S
index aa7e5f5..f26c376 100644
--- a/core/cpu_context_switch.S
+++ b/core/cpu_context_switch.S
@@ -12,8 +12,8 @@ cpu_context_switch:
   pushf              // (eflags)     esp+56
   pushl %cs          // (cs)         esp+52
   pushl $resume_pc   // (ip)         esp+48
-  pushl $0           // (error code) esp+44
-  pushal              // (general reg) esp+12+8*4
+  pushl $0           // (error code) esp+12+8x4
+  pushal             // (general reg) esp+12
   subl $2, %esp      // (alignment)  esp+10
   pushw %ss          //              esp+8
   pushw %ds          //              esp+6
diff --git a/core/interrupt.h b/core/interrupt.h
index 50ac724..14d8dc7 100644
--- a/core/interrupt.h
+++ b/core/interrupt.h
@@ -16,6 +16,7 @@ void print_handler(struct interrupt_frame *frame, ulong error_code);
 void pagefault_handler(struct interrupt_frame *frame, ulong error_code);
 
 // IRQ
+void pit_handler(struct interrupt_frame *frame);
 void keyboard_handler(struct interrupt_frame *frame);
 void timer_handler(struct interrupt_frame *frame);
 void serial_handler(struct interrupt_frame *frame);
diff --git a/core/irq_pit.S b/core/irq_pit.S
new file mode 100644
index 0000000..6684618
--- /dev/null
+++ b/core/irq_pit.S
@@ -0,0 +1,38 @@
+.file "irq_pit.S"
+
+.text
+
+.extern selectNextThread
+
+.globl pit_handler
+.type pit_handler, @function
+pit_handler:         // already got eflags, cs and eip on stack thanks to CPU 
+  pushl $0           // err_code     esp+12+8*4=44
+  pushal             // (general reg) esp+12
+  subl $2, %esp      // (alignment)  esp+10
+  pushw %ss          //              esp+8
+  pushw %ds          //              esp+6
+  pushw %es          //              esp+4
+  pushw %fs          //              esp+2
+  pushw %gs          //              esp
+
+  /* Send EOI to PIC */
+  movb  $0x20, %al
+  outb  %al, $0x20
+
+  pushl %esp
+  call selectNextThread
+  movl %eax,%esp
+
+  /* Restore the CPU context */
+  popw %gs
+  popw %fs
+  popw %es
+  popw %ds
+  popw %ss
+  addl $2,%esp
+  popal
+  addl $4, %esp /* Ignore "error code" */
+
+  /* This restores the eflags, the cs and the eip registers */
+  iret /* equivalent to: popfl ; ret */
diff --git a/core/klibc.c b/core/klibc.c
index fcd64f3..9dffb29 100644
--- a/core/klibc.c
+++ b/core/klibc.c
@@ -80,7 +80,7 @@ void reverse(char s[])
 }
 
 /* K&R */
-int strlen(char s[])
+int strlen(const char s[])
 {
     int i = 0;
     while (s[i] != '\0')
@@ -90,7 +90,7 @@ int strlen(char s[])
 
 /* K&R
  * Returns <0 if s1<s2, 0 if s1==s2, >0 if s1>s2 */
-int strcmp(char s1[], char s2[])
+int strcmp(const char s1[], const char s2[])
 {
     int i;
     for (i = 0; s1[i] == s2[i]; i++) {
@@ -100,6 +100,33 @@ int strcmp(char s1[], char s2[])
     return s1[i] - s2[i];
 }
 
+unsigned int strnlen(const char *s, size_t count)
+{
+    const char *sc;
+
+    for (sc = s; count-- && *sc != '\0'; ++sc)
+        /* nothing */ continue;
+
+    return sc - s;
+}
+
+char *strzcpy(register char *dst, register const char *src, register int len)
+{
+    int i;
+
+    if (len <= 0)
+        return dst;
+
+    for (i = 0; i < len; i++) {
+        dst[i] = src[i];
+        if (src[i] == '\0')
+            return dst;
+    }
+
+    dst[len - 1] = '\0';
+    return dst;
+}
+
 void printf(const char *format, ...)
 {
     va_list ap;
@@ -115,7 +142,8 @@ void puts(const char *str)
     }
 }
 
-void putc(const char str){
+void putc(const char str)
+{
     VGAputc(str);
     serialPutc(str);
 }
diff --git a/core/klibc.h b/core/klibc.h
index d7bdc83..e50b33e 100644
--- a/core/klibc.h
+++ b/core/klibc.h
@@ -14,8 +14,10 @@ void *memcpy(void *dest, const void *src, size_t n);
 void *memset(void *s, int c, size_t n);
 char *itoa(int value, char *str, int base);
 void reverse(char s[]);
-int strlen(char s[]);
-int strcmp(char s1[], char s2[]);
+int strlen(const char s[]);
+unsigned int strnlen(const char * s, size_t count);
+int strcmp(const char s1[], const char s2[]);
+char *strzcpy(char *dst, const char *src, int len);
 void puts(const char *str);
 void putc(const char str);
 void printInt(int integer);
diff --git a/core/kthread.c b/core/kthread.c
new file mode 100644
index 0000000..8ae0978
--- /dev/null
+++ b/core/kthread.c
@@ -0,0 +1,67 @@
+#include "kthread.h"
+#include "list.h"
+#include "alloc.h"
+#include "klibc.h"
+
+static struct kthread *currentThread;
+
+void _kthread_exit(){
+        //TODO 
+        return;
+}
+
+int kthreadSetup(vaddr_t mainStack, size_t mainStackSize){
+        struct kthread * current = (struct kthread *)malloc(sizeof(struct kthread));
+        strzcpy(current->name, "[KINIT]", KTHREAD_NAME_MAX_LENGTH);
+        current->stackAddr = mainStack;
+        current->stackSize = mainStackSize;
+
+        list_singleton(currentThread, current);
+
+        return 0;
+}
+
+struct kthread *createKthread(const char *name, cpu_kstate_function_arg1_t func,
+                              void *args)
+{
+        struct kthread *thread = (struct kthread *)malloc(sizeof(struct kthread));
+        if (!thread)
+                return NULL;
+
+        thread->stackAddr = (vaddr_t) malloc(KTHREAD_DEFAULT_STACK_SIZE);
+        thread->stackSize = KTHREAD_DEFAULT_STACK_SIZE;
+
+        if(!thread->stackAddr)
+                goto free_mem;
+
+        if(name)
+                strzcpy(thread->name, name, KTHREAD_NAME_MAX_LENGTH);
+        else
+                strzcpy(thread->name, "[UNKNOW]", KTHREAD_NAME_MAX_LENGTH);
+
+        if(cpu_kstate_init(&thread->cpuState, (cpu_kstate_function_arg1_t *)func, (vaddr_t)args,
+                    thread->stackAddr, thread->stackSize,
+                    (cpu_kstate_function_arg1_t *)_kthread_exit, 0))
+                goto free_mem;
+
+        list_add_tail(currentThread, thread);
+        return thread;
+free_mem:
+        free((void *)thread->stackAddr);
+        free((void *)thread);
+        return NULL;
+}
+
+void deleteKthread(struct kthread *thread){
+        list_delete(currentThread, thread);
+
+        free((void *)thread->stackAddr);
+        free((void *)thread);
+}
+
+struct cpu_state *selectNextThread(struct cpu_state *prevCpu){
+        currentThread->cpuState = prevCpu;
+        struct kthread *nextThread = currentThread->next;
+        currentThread = nextThread;
+        return nextThread->cpuState;
+}
diff --git a/core/kthread.h b/core/kthread.h
new file mode 100644
index 0000000..178fb82
--- /dev/null
+++ b/core/kthread.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "cpu_context.h"
+#include "mem.h"
+
+#define KTHREAD_NAME_MAX_LENGTH 32
+#define KTHREAD_DEFAULT_STACK_SIZE PAGE_SIZE
+
+struct kthread {
+	char name[KTHREAD_NAME_MAX_LENGTH];
+	struct cpu_state *cpuState;
+	vaddr_t stackAddr;
+	size_t stackSize;
+	struct kthread *next;
+	struct kthread *prev;
+};
+
+
+int kthreadSetup(vaddr_t mainStack, size_t mainStackSize);
+
+struct kthread *createKthread(const char *name, cpu_kstate_function_arg1_t func,
+			      void *args);
+
+void deleteKthread(struct kthread *thread);
+
+struct cpu_state *selectNextThread(struct cpu_state *prev_cpu);
diff --git a/core/main.c b/core/main.c
index c958b59..84b7ba3 100644
--- a/core/main.c
+++ b/core/main.c
@@ -6,11 +6,13 @@
 #include "io.h"
 #include "irq.h"
 #include "klibc.h"
+#include "kthread.h"
 #include "mem.h"
 #include "multiboot.h"
 #include "paging.h"
 #include "pit.h"
 #include "serial.h"
+#include "stack.h"
 #include "stdarg.h"
 #ifdef RUN_TEST
 #include "test.h"
@@ -24,6 +26,18 @@ void cpuid(int code, uint32_t *a, uint32_t *d)
     asm volatile("cpuid" : "=a"(*a), "=d"(*d) : "0"(code) : "ebx", "ecx");
 }
 
+void idleThread(void *arg){
+    (void)arg;
+    while(1)
+        printf(".");
+}
+
+void dashThread(void *arg){
+    (void)arg;
+    while(1)
+        printf("-");
+}
+
 // Multiboot information available here :
 // https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#kernel_002ec
 // https://www.gnu.org/software/grub/manual/multiboot/html_node/Boot-information-format.html#Boot%20information%20format
@@ -99,7 +113,6 @@ void kmain(unsigned long magic, unsigned long addr)
 
     printf("Setting up IRQ handlers\n");
     irqSetRoutine(IRQ_KEYBOARD, keyboard_handler);
-    irqSetRoutine(IRQ_TIMER, timer_handler);
 
     printf("Enabling HW interrupts\n");
     exceptionSetRoutine(EXCEPTION_DOUBLE_FAULT, print_handler);
@@ -110,6 +123,10 @@ void kmain(unsigned long magic, unsigned long addr)
     printf("Setting up Serial link (115200)\n");
     serialSetup(115200);
     allocInit();
+    kthreadSetup(_stack_bottom, (_stack_top - _stack_bottom + 1));
+    createKthread("idle", idleThread, NULL);
+    createKthread("dash", dashThread, NULL);
+    irqSetRoutine(IRQ_TIMER, pit_handler);
 #ifdef RUN_TEST
     run_test();
 #endif
diff --git a/core/stack.c b/core/stack.c
index 21c4ba9..e29037f 100644
--- a/core/stack.c
+++ b/core/stack.c
@@ -2,8 +2,6 @@
 #include "types.h"
 #include "klibc.h"
 
-extern vaddr_t _stack_bottom;
-extern vaddr_t _stack_top;
 void printStackTrace(unsigned int maxFrames)
 {
 #ifdef DEBUG
diff --git a/core/stack.h b/core/stack.h
index a0265cd..a0d6136 100644
--- a/core/stack.h
+++ b/core/stack.h
@@ -1,3 +1,6 @@
 #pragma once
 
+#include "types.h"
+extern vaddr_t _stack_bottom;
+extern vaddr_t _stack_top;
 void printStackTrace(unsigned int maxFrame);