text: // System call numbers
  #define SYS_fork 1
  #define SYS_exit 2
  #define SYS_wait 3
  #define SYS_pipe 4
  #define SYS_read 5
  #define SYS_kill 6
  #define SYS_exec 7
  #define SYS_fstat 8
  #define SYS_chdir 9
  #define SYS_dup 10
  #define SYS_getpid 11
  #define SYS_sbrk 12
  #define SYS_sleep 13
  #define SYS_uptime 14
  #define SYS_open 15
  #define SYS_write 16
  #define SYS_mknod 17
  #define SYS_unlink 18
  #define SYS_link 19
  #define SYS_mkdir 20
  #define SYS_close 21
  #define SYS_exitS 22
  #define SYS_waitpid 23