wearing out. The metal tapes also were dirty, and a slowly renewed felt wiper collected tape debris. The UNISERVO I had a high-speed rewind capability, and multiple drives on the UNIVAC I could rewind while others continued with data processing reads or writes. The later UNISERVO IIA and IIIA omitted the plastic wear tape and felt wipers, since they were primarily used with PET film-base magnetic tape. Both continued the use of single capstan drives and were vacuum column designs. The IIIC and later tapes used NRZI encoding to be compatible with the IBM 729 series tape drives which set the industry standard for data interchange. Ironically, IBM then later switched to phase encoding in its 1600-bit-per-inch tape generation because of its superior data reliability. See also List of UNIVAC products History of computing hardware References Further reading UNIVAC hardware UNIVAC storage devices Computer-related introductions in 1951