UNISERVO
Encyclopedia
The UNISERVO tape drive was the primary I/O
device on the UNIVAC I
computer. Its place in history is assured as it was the first tape drive
for a commercially sold computer.
The UNISERVO used metal tape: a 1/2 in thin strip of nickel
-plated phosphor bronze
(called Vicalloy) 1200 feet long. These metal tape reels were very heavy. 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 was 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
and merging
applications. The data transfers to/from the UNIVAC I processor were fully buffered in a one 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
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.
. 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. Phase encoding
(Manchester) was used to record the information.
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 phase encoded recording and 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.
I/O
I/O may refer to:* Input/output, a system of communication for information processing systems* Input-output model, an economic model of flow prediction between sectors...
device on the UNIVAC I
UNIVAC I
The UNIVAC I was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC...
computer. Its place in history is assured as it was the first tape drive
Tape drive
A tape drive is a data storage device that reads and performs digital recording, 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.A tape drive provides...
for a commercially sold computer.
The UNISERVO used metal tape: a 1/2 in thin strip of nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
-plated phosphor bronze
Phosphor bronze
Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting....
(called Vicalloy) 1200 feet long. These metal tape reels were very heavy. 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 was 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
Sorting is any process of arranging items in some sequence and/or in different sets, and accordingly, it has two common, yet distinct meanings:# ordering: arranging items of the same kind, class, nature, etc...
and merging
Merge algorithm
Merge algorithms are a family of algorithms that run sequentially over multiple sorted lists, typically producing more sorted lists as output. This is well-suited for machines with tape drives...
applications. The data transfers to/from the UNIVAC I processor were fully buffered in a one 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
UNIVAC is the name of a business unit and division of the Remington Rand company formed by the 1950 purchase of the Eckert-Mauchly Computer Corporation, founded four years earlier by ENIAC inventors J. Presper Eckert and John Mauchly, and the associated line of computers which continues to this day...
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
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...
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 motorSynchronous motor
A synchronous electric motor is an AC motor distinguished by a rotor spinning with coils passing magnets at the same rate as the power supply frequency and resulting rotating magnetic field which drives it....
. 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. Phase encoding
Manchester code
In telecommunication and data storage, Manchester code is a line code in which the encoding of each data bit has at least one transition and occupies the same time...
(Manchester) was used to record the information.
The later UNISERVO IIA and IIIA omitted the plastic wear tape and felt wipers, since they were primarily used with PET film
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...
base magnetic tape. Both continued the use of phase encoded recording and single capstan drives and were vacuum column designs. The IIIC and later tapes used NRZI encoding to be compatible with the IBM 729
IBM 729
The IBM 729 Magnetic Tape Unit was IBM's iconic 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...
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 hardwareHistory of computing hardwareThe history of computing hardware is the record of the ongoing effort to make computer hardware faster, cheaper, and capable of storing more data....