diff --git a/01-asm-basics/substitutions.c b/01-asm-basics/substitutions.c
new file mode 100644
index 0000000..c59edcd
--- /dev/null
+++ b/01-asm-basics/substitutions.c
@@ -0,0 +1,60 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <termios.h>
+
+/* Use this variable to remember original terminal attributes. */
+
+struct termios saved_attributes;
+
+void reset_input_mode()
+{
+  tcsetattr (STDIN_FILENO, TCSANOW, &saved_attributes);
+}
+
+void set_input_mode()
+{
+  struct termios tattr;
+  char *name;
+
+  /* Make sure stdin is a terminal. */
+  if (!isatty (STDIN_FILENO))
+    {
+      fprintf (stderr, "Not a terminal.\n");
+      exit (EXIT_FAILURE);
+    }
+
+  /* Save the terminal attributes so we can restore them later. */
+  tcgetattr (STDIN_FILENO, &saved_attributes);
+  atexit (reset_input_mode);
+
+  /* Set the funny terminal modes. */
+  tcgetattr (STDIN_FILENO, &tattr);
+  tattr.c_lflag &= ~(ICANON|ECHO); /* Clear ICANON and ECHO. */
+  tattr.c_cc[VMIN] = 1;
+  tcsetattr (STDIN_FILENO, TCSAFLUSH, &tattr);
+}
+
+void delay(unsigned int ms)
+{
+  usleep(ms * 1000);
+}
+
+char isKeyPressed()
+{
+  char key_handler = 0;
+  read(STDIN_FILENO, &key_handler, 1);
+  if (key_handler > 0)
+  {
+    return 1;
+  }
+  return 0;
+}
+
+//int main()
+//{
+//  set_input_mode();
+//  while (isKeyPressed() == 0) {}
+//  printf("ok");
+//  reset_input_mode();
+//}