The oldest data set, the ITS backup tapes, was chosen for the first migration to TCFS format; it includes tapes written between 1971 and 1990. This chapter discusses many of the specifics of translating and archiving the ITS operating system. Most of the ITS tapes were written on DEC PDP-10's, which used 36-bit words rather than 8-bit bytes. This data set therefore provides a prime example of how platform-independent TCFS is.