The UNISERVO tape drive was the primary I/O device on the

UNIVAC I The UNIVAC I (Universal Automatic Computer I) was the first general-purpose electronic digital computer design for business application produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the invento ...

computer. It was the first

tape drive A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability. ...

for a commercially sold computer. The UNISERVO used metal tape: a thin strip of

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

-plated

phosphor bronze A phosphor is a substance that exhibits the optical phenomenon, phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescence, fluorescent or phosphorescence, phosphorescent sub ...

(called Vicalloy) 1200 feet long. These metal tapes and reels were very heavy with a combined weight of 25lbs. Data was recorded in eight channels on the tape (six for the data value, one parity channel for error checking, and one timing channel) at a density of 128 bits per inch. The tape could be moved at 100 inches per second, giving a nominal transfer rate of 12,800 characters per second. Data were recorded in fixed size blocks of 60 words of 12 characters each. Making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. The UNISERVO supported both forward and backward modes on read or write operation. This offered significant advantages in data

sorting Sorting refers to ordering data in an increasing or decreasing manner according to some linear relationship among the data items. # ordering: arranging items in a sequence ordered by some criterion; # categorizing: grouping items with similar p ...

and merging applications. The data transfers to/from the UNIVAC I processor were fully buffered in a single block dedicated memory, permitting instruction execution in parallel with tape movement and data transfer. The internal serial data path permitted inserting a tape data block into main memory in one instruction.

UNIVAC UNIVAC (Universal Automatic Computer) was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and ...

continued to use the name UNISERVO for later models of tape drive (e.g., UNISERVO II, UNISERVO IIIC, UNISERVO VIII-C) for later computers in their product line. The UNISERVO II could read metal tapes from the UNIVAC I as well as use higher-density PET film base/ferric oxide media tapes that became the industry standard. While UNIVAC was first with computer tape, and had higher performance than contemporary IBM tape drives, IBM was able to set the data interchange standard. UNIVAC was later forced to be compatible with the IBM technology.

Technical details

The tape motion in the UNISERVO I was controlled by a single capstan connected to a

synchronous motor A synchronous electric motor is an AC electric motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integer number of AC cycles. Sync ...

. Supply and take-up reel motion was buffered via a complex pulley-string-spring arrangement, as the design was prior to the invention of the vacuum column buffer. The tape drive contained a permanent leader, and each tape reel had a connector link to the leader. The nickel-plated phosphor bronze tapes were very abrasive, and to counter this problem a thin plastic wear tape was slowly moved over the recording head, between the head and the tape, preventing the recording head from quickly 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 The IBM 729 Magnetic Tape Unit was IBM's tape mass storage system from the late 1950s through the mid-1960s. Part of the IBM 7-track family of tape units, it was used on late 700, most 7000 and many 1400 series computers. Like its predecessor, ...

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.

Technical details

See also

References

Further reading