diff --git a/nanos-lite/.gitignore b/nanos-lite/.gitignore
new file mode 100644
index 0000000..5d12530
--- /dev/null
+++ b/nanos-lite/.gitignore
@@ -0,0 +1,8 @@
+*.*
+*
+!*/
+!Makefile*
+!*.[cSh]
+!.gitignore
+!README.md
+!resources/logo.txt
diff --git a/nanos-lite/Makefile b/nanos-lite/Makefile
new file mode 100644
index 0000000..64e02b0
--- /dev/null
+++ b/nanos-lite/Makefile
@@ -0,0 +1,34 @@
+#HAS_NAVY = 1
+RAMDISK_FILE = build/ramdisk.img
+
+NAME = nanos-lite
+SRCS = $(shell find -L ./src/ -name "*.c" -o -name "*.cpp" -o -name "*.S")
+include $(AM_HOME)/Makefile
+
+ifeq ($(ARCH),native)
+ISA = am_native
+else
+INC_PATH += include $(NAVY_HOME)/libs/libc/include
+endif
+
+./src/resources.S: $(RAMDISK_FILE)
+	@touch $@
+
+ifeq ($(HAS_NAVY),)
+files = $(RAMDISK_FILE) src/files.h src/syscall.h
+# create an empty file if it does not exist
+$(foreach f,$(files),$(if $(wildcard $f),, $(shell touch $f)))
+else
+
+ifeq ($(wildcard $(NAVY_HOME)/libs/libos/src/syscall.h),)
+  $(error $$NAVY_HOME must be a Navy-apps repo)
+endif
+
+update:
+	$(MAKE) -s -C $(NAVY_HOME) ISA=$(ISA) ramdisk
+	@ln -sf $(NAVY_HOME)/build/ramdisk.img $(RAMDISK_FILE)
+	@ln -sf $(NAVY_HOME)/build/ramdisk.h src/files.h
+	@ln -sf $(NAVY_HOME)/libs/libos/src/syscall.h src/syscall.h
+
+.PHONY: update
+endif
diff --git a/nanos-lite/README.md b/nanos-lite/README.md
new file mode 100644
index 0000000..883c53d
--- /dev/null
+++ b/nanos-lite/README.md
@@ -0,0 +1,15 @@
+# Nanos-lite
+
+Nanos-lite is the simplified version of Nanos (http://cslab.nju.edu.cn/opsystem).
+It is ported to the [AM project](https://github.com/NJU-ProjectN/abstract-machine.git).
+It is a two-tasking operating system with the following features
+* ramdisk device drivers
+* ELF program loader
+* memory management with paging
+* a simple file system
+  * with fix number and size of files
+  * without directory
+  * some device files
+* 9 system calls
+  * open, read, write, lseek, close, gettimeofday, brk, exit, execve
+* scheduler with two tasks
diff --git a/nanos-lite/include/common.h b/nanos-lite/include/common.h
new file mode 100644
index 0000000..a5abb87
--- /dev/null
+++ b/nanos-lite/include/common.h
@@ -0,0 +1,15 @@
+#ifndef __COMMON_H__
+#define __COMMON_H__
+
+/* Uncomment these macros to enable corresponding functionality. */
+//#define HAS_CTE
+//#define HAS_VME
+//#define MULTIPROGRAM
+//#define TIME_SHARING
+
+#include <am.h>
+#include <klib.h>
+#include <klib-macros.h>
+#include <debug.h>
+
+#endif
diff --git a/nanos-lite/include/debug.h b/nanos-lite/include/debug.h
new file mode 100644
index 0000000..b66a047
--- /dev/null
+++ b/nanos-lite/include/debug.h
@@ -0,0 +1,30 @@
+#ifndef __DEBUG_H__
+#define __DEBUG_H__
+
+#include <common.h>
+
+#define Log(format, ...) \
+  printf("\33[1;35m[%s,%d,%s] " format "\33[0m\n", \
+      __FILE__, __LINE__, __func__, ## __VA_ARGS__)
+
+#undef panic
+#define panic(format, ...) \
+  do { \
+    Log("\33[1;31msystem panic: " format, ## __VA_ARGS__); \
+    halt(1); \
+  } while (0)
+
+#ifdef assert
+# undef assert
+#endif
+
+#define assert(cond) \
+  do { \
+    if (!(cond)) { \
+      panic("Assertion failed: %s", #cond); \
+    } \
+  } while (0)
+
+#define TODO() panic("please implement me")
+
+#endif
diff --git a/nanos-lite/include/fs.h b/nanos-lite/include/fs.h
new file mode 100644
index 0000000..8fc94a2
--- /dev/null
+++ b/nanos-lite/include/fs.h
@@ -0,0 +1,10 @@
+#ifndef __FS_H__
+#define __FS_H__
+
+#include <common.h>
+
+#ifndef SEEK_SET
+enum {SEEK_SET, SEEK_CUR, SEEK_END};
+#endif
+
+#endif
diff --git a/nanos-lite/include/memory.h b/nanos-lite/include/memory.h
new file mode 100644
index 0000000..c1f72ba
--- /dev/null
+++ b/nanos-lite/include/memory.h
@@ -0,0 +1,14 @@
+#ifndef __MEMORY_H__
+#define __MEMORY_H__
+
+#include <common.h>
+
+#ifndef PGSIZE
+#define PGSIZE 4096
+#endif
+
+#define PG_ALIGN __attribute((aligned(PGSIZE)))
+
+void* new_page(size_t);
+
+#endif
diff --git a/nanos-lite/include/proc.h b/nanos-lite/include/proc.h
new file mode 100644
index 0000000..f628bf2
--- /dev/null
+++ b/nanos-lite/include/proc.h
@@ -0,0 +1,21 @@
+#ifndef __PROC_H__
+#define __PROC_H__
+
+#include <common.h>
+#include <memory.h>
+
+#define STACK_SIZE (8 * PGSIZE)
+
+typedef union {
+  uint8_t stack[STACK_SIZE] PG_ALIGN;
+  struct {
+    Context *cp;
+    AddrSpace as;
+    // we do not free memory, so use `max_brk' to determine when to call _map()
+    uintptr_t max_brk;
+  };
+} PCB;
+
+extern PCB *current;
+
+#endif
diff --git a/nanos-lite/resources/logo.txt b/nanos-lite/resources/logo.txt
new file mode 100644
index 0000000..0a0bccd
--- /dev/null
+++ b/nanos-lite/resources/logo.txt
@@ -0,0 +1,29 @@
+######################%'``|######################$
+###################$` ..`.  '&###################$
+#################$` .`::::'`  '&#################$
+###############$` .`::;!;::::`. '&###############$
+#############$` .`:::::|$%;::::`  '&#############$
+###########$` .'::::::!%$$$%;::::`. '&###########$
+#########$` .'::::::!%$$$$$%;::::::`  '&#########$
+#######$` .'::::::!%$%|$$$$%;::::::::`. '&#######$
+#####$` .'::::::!%$%;:|$$$$|;::::::::::`  '&#####$
+###$` .';;;;;;!%$%;;;;|$$$$|;::::;|%!::::`. '&###$
+#&' .';;;%%!!%$%;;;;;;%$$$$|;;;;;;;|$%!;:::`. '@#$
+%.  ';;;;;|$$%!;;;;;;!%$$$$!;;;;;!%$%%$%!;;:`  '&$
+|    `;;;;;;|$%!;;;;;!$$$$%!;;;!%$%!;;;;;;:`   .%$
+@:  ;!``;;;;;;;;;;;;;|$$$$%!;!%$%!;;;;;;:`'!'  :@$
+;   '%$!``;;;;;;;;;;;|$$$$%!%$%!;;;;;;:`'|$|`   |$
+|    .:%$!`';;;;;;;;!%$$$$$$%!;;;;;;:`'|$|'    .%$
+#$`    .:%$|`';;;;;;!%$$$$%!;;;;;;:`'|$|'     ;##$
+###$`    .:%$|`';;;;;!%$%|!;;;;;;`'%$|'     ;####$
+#####$`    .:%$|`';!!!!!!!!!!!;`'%$%'     ;######$
+#######$`    .:$$|`';!!!!!!!;`'%$%'     ;########$
+#########$`    .:$$|`';!!!;`'%$%'     ;##########$
+###########$`    .:$&|`.`.'%&%'     ;@###########$
+#############$`    .:$&$$&&%'     ;##############$
+###############$`    .:$&%'     ;@###############$
+#################$`           ;##################$
+
+                  **Project-N**
+ Nanjing University Computer System Project Series
+       Build a computer system from scratch!
diff --git a/nanos-lite/src/.gitignore b/nanos-lite/src/.gitignore
new file mode 100644
index 0000000..225938b
--- /dev/null
+++ b/nanos-lite/src/.gitignore
@@ -0,0 +1,2 @@
+files.h
+syscall.h
diff --git a/nanos-lite/src/device.c b/nanos-lite/src/device.c
new file mode 100644
index 0000000..37a2f3d
--- /dev/null
+++ b/nanos-lite/src/device.c
@@ -0,0 +1,36 @@
+#include <common.h>
+
+#if defined(MULTIPROGRAM) && !defined(TIME_SHARING)
+# define MULTIPROGRAM_YIELD() yield()
+#else
+# define MULTIPROGRAM_YIELD()
+#endif
+
+#define NAME(key) \
+  [AM_KEY_##key] = #key,
+
+static const char *keyname[256] __attribute__((used)) = {
+  [AM_KEY_NONE] = "NONE",
+  AM_KEYS(NAME)
+};
+
+size_t serial_write(const void *buf, size_t offset, size_t len) {
+  return 0;
+}
+
+size_t events_read(void *buf, size_t offset, size_t len) {
+  return 0;
+}
+
+size_t dispinfo_read(void *buf, size_t offset, size_t len) {
+  return 0;
+}
+
+size_t fb_write(const void *buf, size_t offset, size_t len) {
+  return 0;
+}
+
+void init_device() {
+  Log("Initializing devices...");
+  ioe_init();
+}
diff --git a/nanos-lite/src/fs.c b/nanos-lite/src/fs.c
new file mode 100644
index 0000000..a9d2670
--- /dev/null
+++ b/nanos-lite/src/fs.c
@@ -0,0 +1,36 @@
+#include <fs.h>
+
+typedef size_t (*ReadFn) (void *buf, size_t offset, size_t len);
+typedef size_t (*WriteFn) (const void *buf, size_t offset, size_t len);
+
+typedef struct {
+  char *name;
+  size_t size;
+  size_t disk_offset;
+  ReadFn read;
+  WriteFn write;
+} Finfo;
+
+enum {FD_STDIN, FD_STDOUT, FD_STDERR, FD_FB};
+
+size_t invalid_read(void *buf, size_t offset, size_t len) {
+  panic("should not reach here");
+  return 0;
+}
+
+size_t invalid_write(const void *buf, size_t offset, size_t len) {
+  panic("should not reach here");
+  return 0;
+}
+
+/* This is the information about all files in disk. */
+static Finfo file_table[] __attribute__((used)) = {
+  [FD_STDIN]  = {"stdin", 0, 0, invalid_read, invalid_write},
+  [FD_STDOUT] = {"stdout", 0, 0, invalid_read, invalid_write},
+  [FD_STDERR] = {"stderr", 0, 0, invalid_read, invalid_write},
+#include "files.h"
+};
+
+void init_fs() {
+  // TODO: initialize the size of /dev/fb
+}
diff --git a/nanos-lite/src/irq.c b/nanos-lite/src/irq.c
new file mode 100644
index 0000000..624a0ac
--- /dev/null
+++ b/nanos-lite/src/irq.c
@@ -0,0 +1,14 @@
+#include <common.h>
+
+static Context* do_event(Event e, Context* c) {
+  switch (e.event) {
+    default: panic("Unhandled event ID = %d", e.event);
+  }
+
+  return c;
+}
+
+void init_irq(void) {
+  Log("Initializing interrupt/exception handler...");
+  cte_init(do_event);
+}
diff --git a/nanos-lite/src/loader.c b/nanos-lite/src/loader.c
new file mode 100644
index 0000000..9e908f3
--- /dev/null
+++ b/nanos-lite/src/loader.c
@@ -0,0 +1,22 @@
+#include <proc.h>
+#include <elf.h>
+
+#ifdef __LP64__
+# define Elf_Ehdr Elf64_Ehdr
+# define Elf_Phdr Elf64_Phdr
+#else
+# define Elf_Ehdr Elf32_Ehdr
+# define Elf_Phdr Elf32_Phdr
+#endif
+
+static uintptr_t loader(PCB *pcb, const char *filename) {
+  TODO();
+  return 0;
+}
+
+void naive_uload(PCB *pcb, const char *filename) {
+  uintptr_t entry = loader(pcb, filename);
+  Log("Jump to entry = %p", entry);
+  ((void(*)())entry) ();
+}
+
diff --git a/nanos-lite/src/main.c b/nanos-lite/src/main.c
new file mode 100644
index 0000000..883600b
--- /dev/null
+++ b/nanos-lite/src/main.c
@@ -0,0 +1,37 @@
+#include <common.h>
+
+void init_mm(void);
+void init_device(void);
+void init_ramdisk(void);
+void init_irq(void);
+void init_fs(void);
+void init_proc(void);
+
+int main() {
+  extern const char logo[];
+  printf("%s", logo);
+  Log("'Hello World!' from Nanos-lite");
+  Log("Build time: %s, %s", __TIME__, __DATE__);
+
+  init_mm();
+
+  init_device();
+
+  init_ramdisk();
+
+#ifdef HAS_CTE
+  init_irq();
+#endif
+
+  init_fs();
+
+  init_proc();
+
+  Log("Finish initialization");
+
+#ifdef HAS_CTE
+  yield();
+#endif
+
+  panic("Should not reach here");
+}
diff --git a/nanos-lite/src/mm.c b/nanos-lite/src/mm.c
new file mode 100644
index 0000000..661b580
--- /dev/null
+++ b/nanos-lite/src/mm.c
@@ -0,0 +1,31 @@
+#include <memory.h>
+
+static void *pf = NULL;
+
+void* new_page(size_t nr_page) {
+  return NULL;
+}
+
+#ifdef HAS_VME
+static void* pg_alloc(int n) {
+  return NULL;
+}
+#endif
+
+void free_page(void *p) {
+  panic("not implement yet");
+}
+
+/* The brk() system call handler. */
+int mm_brk(uintptr_t brk) {
+  return 0;
+}
+
+void init_mm() {
+  pf = (void *)ROUNDUP(heap.start, PGSIZE);
+  Log("free physical pages starting from %p", pf);
+
+#ifdef HAS_VME
+  vme_init(pg_alloc, free_page);
+#endif
+}
diff --git a/nanos-lite/src/proc.c b/nanos-lite/src/proc.c
new file mode 100644
index 0000000..70efb8f
--- /dev/null
+++ b/nanos-lite/src/proc.c
@@ -0,0 +1,33 @@
+#include <proc.h>
+
+#define MAX_NR_PROC 4
+
+static PCB pcb[MAX_NR_PROC] __attribute__((used)) = {};
+static PCB pcb_boot = {};
+PCB *current = NULL;
+
+void switch_boot_pcb() {
+  current = &pcb_boot;
+}
+
+void hello_fun(void *arg) {
+  int j = 1;
+  while (1) {
+    Log("Hello World from Nanos-lite with arg '%p' for the %dth time!", (uintptr_t)arg, j);
+    j ++;
+    yield();
+  }
+}
+
+void init_proc() {
+  switch_boot_pcb();
+
+  Log("Initializing processes...");
+
+  // load program here
+
+}
+
+Context* schedule(Context *prev) {
+  return NULL;
+}
diff --git a/nanos-lite/src/ramdisk.c b/nanos-lite/src/ramdisk.c
new file mode 100644
index 0000000..0e33d58
--- /dev/null
+++ b/nanos-lite/src/ramdisk.c
@@ -0,0 +1,33 @@
+#include <common.h>
+
+extern uint8_t ramdisk_start;
+extern uint8_t ramdisk_end;
+#define RAMDISK_SIZE ((&ramdisk_end) - (&ramdisk_start))
+
+/* The kernel is monolithic, therefore we do not need to
+ * translate the address `buf' from the user process to
+ * a physical one, which is necessary for a microkernel.
+ */
+
+/* read `len' bytes starting from `offset' of ramdisk into `buf' */
+size_t ramdisk_read(void *buf, size_t offset, size_t len) {
+  assert(offset + len <= RAMDISK_SIZE);
+  memcpy(buf, &ramdisk_start + offset, len);
+  return len;
+}
+
+/* write `len' bytes starting from `buf' into the `offset' of ramdisk */
+size_t ramdisk_write(const void *buf, size_t offset, size_t len) {
+  assert(offset + len <= RAMDISK_SIZE);
+  memcpy(&ramdisk_start + offset, buf, len);
+  return len;
+}
+
+void init_ramdisk() {
+  Log("ramdisk info: start = %p, end = %p, size = %d bytes",
+      &ramdisk_start, &ramdisk_end, RAMDISK_SIZE);
+}
+
+size_t get_ramdisk_size() {
+  return RAMDISK_SIZE;
+}
diff --git a/nanos-lite/src/syscall.c b/nanos-lite/src/syscall.c
new file mode 100644
index 0000000..9ec6dc0
--- /dev/null
+++ b/nanos-lite/src/syscall.c
@@ -0,0 +1,10 @@
+#include <common.h>
+#include "syscall.h"
+void do_syscall(Context *c) {
+  uintptr_t a[4];
+  a[0] = c->GPR1;
+
+  switch (a[0]) {
+    default: panic("Unhandled syscall ID = %d", a[0]);
+  }
+}
diff --git a/nemu/configs/tmp_defconfig b/nemu/configs/tmp_defconfig
deleted file mode 100644
index 3cb29f8..0000000
--- a/nemu/configs/tmp_defconfig
+++ /dev/null
@@ -1,3 +0,0 @@
-# CONFIG_ITRACE is not set
-CONFIG_PMEM_MALLOC=y
-CONFIG_DEVICE=y