CISCO 1720 IOS PERDU

bonjour;

j'ai le problème de IOS si je comprend, c.a.d. rom vide et mon routeur CISCO 1720 affiche par hyperterminal les messages suivantes :

System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
C1700 platform with 16384 Kbytes of main memory

device does not contain a valid magic number
boot: cannot open "flash:"
boot: cannot determine first file name on device "flash:"
ý
System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
C1700 platform with 16384 Kbytes of main memory

device does not contain a valid magic number
boot: cannot open "flash:"
boot: cannot determine first file name on device "flash:"

System Bootstrap, Version 12.0(3)T, RELEASE SOFTWARE (fc1)
Copyright (c) 1999 by cisco Systems, Inc.
C1700 platform with 16384 Kbytes of main memory

rommon 1 >

que je doit faire svp, l'encien firmware cé : c1700-y-mz.120-1.AX3