1.
Magnetic tape data storage
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Magnetic tape data storage is a system for storing digital information on magnetic tape using digital recording. Modern magnetic tape is most commonly packaged in cartridges and cassettes, the device that performs writing or reading of data is a tape drive. Autoloaders and tape libraries automate cartridge handling, for example, a common cassette-based format is Linear Tape-Open, which comes in a variety of densities and is manufactured by several companies. Sony announced in 2014 that they had developed a storage technology with the highest reported magnetic tape data density,148 Gbit/in². Initially, magnetic tape for storage was wound on 10. 5-inch reels. This de facto standard for computer systems persisted through the late 1980s. Tape cartridges and cassettes were available as early as the mid-1970s and were used with small computer systems. With the introduction of the IBM3480 cartridge in 1984, large computer systems started to move away from open reel tapes, magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The UNISERVO drive recording medium was a metal strip of 0. 5-inch wide nickel-plated phosphor bronze. Recording density was 128 characters per inch on eight tracks at a speed of 100 in/s. Of the eight tracks, six were data, one was a parity track, making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. A small reel of mylar tape provided separation from the metal tape, IBM computers from the 1950s used ferrous-oxide coated tape similar to that used in audio recording. IBMs technology soon became the de facto industry standard, magnetic tape dimensions were 0. 5-inch wide and wound on removable reels up to 10.5 inches in diameter. Different tape lengths were available with 1,200 feet and 2,400 feet on mil, during the 1980s, longer tape lengths such as 3,600 feet became available using a much thinner PET film. Most tape drives could support a maximum size of 10.5 inches. CDC used IBM compatible 1/2 inch magnetic tapes, but also offered a 1 inch wide variant, a so-called mini-reel was common for smaller data sets, such as for software distribution. These were 7-inch reels, often with no fixed length—the tape was sized to fit the amount of data recorded on it as a cost-saving measure. Early IBM tape drives, such as the IBM727 and IBM729, were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long u-shaped loops of tape
2.
Digital Equipment Corporation
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Digital Equipment Corporation, also known as DEC and using the trademark Digital, was a major American company in the computer industry from the 1950s to the 1990s. DEC was a vendor of computer systems, including computers, software. Their PDP and successor VAX products were the most successful of all minicomputers in terms of sales, DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence, however, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard in May 2002, as of 2007 some of DECs product lines were still produced under the HP name. From 1957 until 1992, DECs headquarters were located in a wool mill in Maynard. DEC was acquired in June 1998 by Compaq, which merged with Hewlett-Packard in May 2002. Some parts of DEC, notably the business and the Hudson. Initially focusing on the end of the computer market allowed DEC to grow without its potential competitors making serious efforts to compete with them. Their PDP series of machines became popular in the 1960s, especially the PDP-8, looking to simplify and update their line, DEC replaced most of their smaller machines with the PDP-11 in 1970, eventually selling over 600,000 units and cementing DECs position in the industry. Originally designed as a follow-on to the PDP-11, DECs VAX-11 series was the first widely used 32-bit minicomputer and these systems were able to compete in many roles with larger mainframe computers, such as the IBM System/370. The VAX was a best-seller, with over 400,000 sold, at its peak, DEC was the second largest employer in Massachusetts, second only to the Massachusetts State Government. The rapid rise of the business microcomputer in the late 1980s, DECs last major attempt to find a space in the rapidly changing market was the DEC Alpha 64-bit RISC instruction set architecture. DEC initially started work on Alpha as a way to re-implement their VAX series, DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence, however, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard in May 2002, as of 2007 some of DECs product lines were still produced under the HP name
3.
Quantum Corporation
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It also sells scalable file storage systems and archive software and appliances for managing data. The companys headquarters is in San Jose, California, from its founding in 1980 until 2001, it was also a major disk storage manufacturer, and was based in Milpitas, California. Quantum sold its disk drive business to Maxtor in 2001. Early on, the company designed smaller ST-506-compatible versions of its hard drives, in 1985, it introduced the Plus Hardcard, which was essentially a smaller version of the Q500, designed to fit in an ISA slot. In 1986, Quantum entered the then-new SCSI market with the Q280 80MB drive, when the company was started, low end drives generally used stepper motors, which were slow, noisy, and prone to reliability problems. Quantum developed a positioning system to guide the actuator arm in gross motor movements. This glass scale solution saved quite a bit of hardware as it required a single 8-bit microcontroller to handle the entire servo system. The Q2000 and Q4000 were the first drives to use this technology, later on, as track pitch narrowed, diffraction became a problem, and the decision was made to discontinue the system in favor of a fully magnetic embedded servo. The last drives to use the optical assist system were the ProDrive LPS120 and 240 Gemini models, the Fireball brand of hard drives were manufactured between 1995 and 2001. In 1995,540 MB Fireball hard drives using ATA and SCSI were available, in 1997, the Fireball ST, available in 1.6 GB to 6.4 GB capacities, was considered a top performer, while the Fireball TM was significantly slower. After some success with the Fireball AT1080 and Fireball AT1280, later versions of the Fireball series reversed this trend, and eventually a 7200 rpm Fireball Plus ATA version was released. The first of the Plus series was the Fireball Plus KA, a drive available in sizes up to 18.2 gigabytes, the Bigfoot brand of hard drives were available during the late 1990s and generally had lower costs per megabyte. It used a low-profile 5. 25-inch form factor and larger disks to increase capacity without forcing an increase in areal density. However, the Bigfoot drives had slow spindles, and the larger disk diameters meant the heads had to move farther when seeking and they were thus generally disliked by power users, and found their way mostly into inexpensive, brand-name PCs. In July 1994, Quantum purchased DECs data storage division for $348 million and this gave Quantum access to the DLT streaming tape system, as well as Digitals design team in Shrewsbury, Massachusetts, which previously designed the RZ72 SCSI disk. The StorageWorks brand of disk arrays was not included in the deal, after the acquisition, Quantum tasked the Shrewsbury design team with developing the Atlas series of SCSI disks. Quantums Milpitas design team created the Viking, Phoenix and Katana designs, due to widespread Y2K fears, and the associated desire to safeguard data, the DLT product line had a large increase in sales in the late 1990s. As a result, Quantum split the company into two parts, one for the DLT products, and one for hard disk drives, by 2000, the hard drive market was becoming less profitable. Quantum decided to sell its hard drive division to Maxtor at this time
4.
MicroVAX
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The MicroVAX was a family of low-cost minicomputers developed and manufactured by Digital Equipment Corporation. The first model, the MicroVAX I, was introduced in 1984, the MicroVAX family used processors that implemented the VAX instruction set architecture and was succeeded by the VAX4000. The MicroVAX I, code named Seahorse, introduced in October 1984, was one of DECs first VAX computers to use very-large-scale integration technology, the KA610 CPU module contained two custom chips which implemented the ALU and FPU while TTLs were used for everything else. Two variants of the floating point chips were supported, with the chips differing by the type of floating point instructions supported, F and G, the MicroVAX II, code named Mayflower, was a mid-range MicroVAX introduced in May 1985. It ran VAX/VMS or, alternatively, ULTRIX, the DEC native Unix operating system and it used the KA630-AA CPU module, a quad-height Q22-Bus module, which featured a MicroVAX78032 microprocessor and a MicroVAX78132 floating-point coprocessor operating at 5 MHz. Two gate arrays on the module implemented the external interface for the microprocessor, Q22-bus interface, the module also contained 1 MB of memory, an interval timer, two ROMs for the boot and diagnostic facility, a DZ console serial line unit and a time-of-year clock. A 50-pin connector for a ribbon cable near the top corner of the module provided the means by which more memory was added to the system. The MicroVAX II supported 1 to 16 MB of memory through zero, the MS630 memory expansion module was used for expanding memory capacity. Four variants of the MS630 existed, the 1 MB MS630-AA,2 MB MS630-BA,4 MB MS630-BB, the MS630-AA was a dual-height module, whereas the MS630-BA, MS630-BB and MS630-CA were quad-height modules. These modules used 256 Kb DRAMs and were protected by byte-parity, the modules connected to the CPU module via the backplane through the C and D rows and a 50-conductor ribbon cable. The backplane served as the bus and the ribbon cable as the data bus. The MicroVAX II came in three models of enclosure, BA23 BA123 630QE - A deskside enclosure, KA620 referred to a single-board MicroVAX II designed for automatic test equipment and manufacturing applications which only ran DECs real-time VAXELN operating system. A KA620 with 1 MB of memory bundled with the VAXELN Run-Time Package 2.3 was priced at US$5,000, mira referred to a fault-tolerant configuration of the MicroVAX II developed by DECs European Centre for Special Systems located in Annecy in France. The system consisted of two MicroVAX78032 microprocessors, an active and standby microprocessor in a box, connected by Ethernet. When a fault was detected in the microprocessor, the workload was switched over to the standby microprocessor. A MicroVAX II in BA213 enclosure, bA23- or BA123-enclosure MicroVAX upgraded with KA650 CPU module containing a CVAX chip set. BA23- or BA123-enclosure MicroVAX upgraded with KA655 CPU module, bA23- or BA123-enclosure MicroVAX upgraded with KA660 CPU module. The MicroVAX2000, code named TeamMate, was a low-cost MicroVAX introduced on 10 February 1987, in January 1987, the MicroVAX2000 was the first VAX system targeted at both universities and VAX programmers who wanted to work from remote locations
5.
PDP-11
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The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 had several innovative features, and was easier to program than its predecessors through the additional general-purpose registers. The PDP-11 replaced the PDP-8 in many applications, although both product lines lived in parallel for more than 10 years. In total, around 600,000 PDP-11s of all models were sold and its successor in the mid-range minicomputer niche was the 32-bit VAX-11, named as a nod to the PDP-11s popularity. The PDP-11 is considered by experts to be the most popular minicomputer ever. Design features of the PDP-11 influenced the design of most late-1970s computer systems including the Intel x86, design features of PDP-11 operating systems, as well as other operating systems from Digital Equipment, influenced the design of other operating systems such as CP/M and hence also MS-DOS. For a decade, the PDP-11 was the smallest system that could run Unix and it is commonly stated that the C programming language took advantage of several low-level PDP-11–dependent programming features, albeit not originally by design. In 1967–68, DEC engineers designed a 16-bit, word-addressed machine, management cancelled the project and some of the engineers later left DEC and produced it as the Data General Nova. A subsequent effort, code-named Desk Calculator, looked at a variety of options before choosing what became the 16-bit PDP-11, DECs previous PDP-8 and PDP-9 had 12- and 18-bit words, the PDP-11 family was announced in January 1970 and shipments began early that year. DEC sold over 170,000 PDP-11s in the 1970s, initially manufactured of small-scale transistor–transistor logic, a single-board large scale integration version of the processor was developed in 1975. A two-or-three-chip processor, the J-11 was developed in 1979, the last models of the PDP-11 line were the PDP-11/94 and -11/93 introduced in 1990. The PDP-11 processor architecture has an orthogonal instruction set. For example, instead of such as load and store. More complex instructions such as add likewise can have memory, register, input, most operands can apply any of eight addressing modes to eight registers. The addressing modes provide register, immediate, absolute, relative, deferred, and indexed addressing, use of relative addressing lets a machine-language program be position-independent. Early models of the PDP-11 had no dedicated bus for input/output, an input/output device determined the memory addresses to which it would respond, and specified its own interrupt vector and interrupt priority. DEC openly published the basic Unibus specifications, even offering prototyping bus interface circuit boards, the Unibus made the PDP-11 suitable for custom peripherals. Higher-performance members of the PDP-11 family, starting with the PDP-11/45 Unibus and 11/83 Q-bus systems, instead, memory was interfaced by dedicated circuitry and space in the CPU cabinet, while the Unibus continued to be used for I/O only
6.
Minicomputer
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A minicomputer, or colloquially mini, is a class of smaller computers that developed in the mid-1960s and sold for much less than mainframe and mid-size computers from IBM and its direct competitors. The class formed a group with its own software architectures. Minis were designed for control, instrumentation, human interaction, and communication switching as distinct from calculation, many were sold indirectly to Original Equipment Manufacturers for final end use application. During the two decade lifetime of the class, almost 100 companies formed and only a half dozen remained. They usually took up one or a few 19-inch rack cabinets, the definition of minicomputer is vague with the consequence that there are a number of candidates for the first minicomputer. An early and highly successful minicomputer was Digital Equipment Corporations 12-bit PDP-8, later versions of the PDP-8 took advantage of small-scale integrated circuits. The important precursors of the PDP-8 include the PDP-5, LINC, the TX-0, the TX-2, DEC gave rise to a number of minicomputer companies along Massachusetts Route 128, including Data General, Wang Laboratories, Apollo Computer, and Prime Computer. Minicomputers were also known as midrange computers and they grew to have relatively high processing power and capacity. They were used in manufacturing process control, telephone switching and to control laboratory equipment, in the 1970s, they were the hardware that was used to launch the computer-aided design industry and other similar industries where a smaller dedicated system was needed. The 7400 series of TTL integrated circuits started appearing in minicomputers in the late 1960s, the 74181 arithmetic logic unit was commonly used in the CPU data paths. Each 74181 had a bus width of four bits, hence the popularity of bit-slice architecture, some scientific computers, such as the Nicolet 1080, would use the 7400 series in groups of five ICs for their uncommon twenty bits architecture. Starting in the 1980s, many minicomputers used VLSI circuits, the result was that minicomputers and computer terminals were replaced by networked workstations, file servers and PCs in some installations, beginning in the latter half of the 1980s. Also, the Microsoft Windows series of operating systems, beginning with Windows NT, now included server versions that supported preemptive multitasking, Digital Equipment Corporation was once the leading minicomputer manufacturer, at one time the second-largest computer company after IBM. DEC was sold to Compaq in 1998, while Data General was acquired by EMC Corporation, today only a few proprietary minicomputer architectures survive. The IBM System/38 operating system, which introduced many advanced concepts, realising the importance of the myriad lines of legacy code written, AS stands for Application System. Great efforts were made by IBM to enable programs written for the System/34. The AS/400 was replaced by the iSeries, which was replaced by the System i. In 2008, the System i was replaced by the IBM Power Systems, by contrast, competing proprietary computing architectures from the early 1980s, such as DECs VAX, Wang VS and Hewlett Packards HP3000 have long been discontinued without a compatible upgrade path
7.
Data cartridge (tape)
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Magnetic tape data storage is a system for storing digital information on magnetic tape using digital recording. Modern magnetic tape is most commonly packaged in cartridges and cassettes, the device that performs writing or reading of data is a tape drive. Autoloaders and tape libraries automate cartridge handling, for example, a common cassette-based format is Linear Tape-Open, which comes in a variety of densities and is manufactured by several companies. Sony announced in 2014 that they had developed a storage technology with the highest reported magnetic tape data density,148 Gbit/in². Initially, magnetic tape for storage was wound on 10. 5-inch reels. This de facto standard for computer systems persisted through the late 1980s. Tape cartridges and cassettes were available as early as the mid-1970s and were used with small computer systems. With the introduction of the IBM3480 cartridge in 1984, large computer systems started to move away from open reel tapes, magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The UNISERVO drive recording medium was a metal strip of 0. 5-inch wide nickel-plated phosphor bronze. Recording density was 128 characters per inch on eight tracks at a speed of 100 in/s. Of the eight tracks, six were data, one was a parity track, making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. A small reel of mylar tape provided separation from the metal tape, IBM computers from the 1950s used ferrous-oxide coated tape similar to that used in audio recording. IBMs technology soon became the de facto industry standard, magnetic tape dimensions were 0. 5-inch wide and wound on removable reels up to 10.5 inches in diameter. Different tape lengths were available with 1,200 feet and 2,400 feet on mil, during the 1980s, longer tape lengths such as 3,600 feet became available using a much thinner PET film. Most tape drives could support a maximum size of 10.5 inches. CDC used IBM compatible 1/2 inch magnetic tapes, but also offered a 1 inch wide variant, a so-called mini-reel was common for smaller data sets, such as for software distribution. These were 7-inch reels, often with no fixed length—the tape was sized to fit the amount of data recorded on it as a cost-saving measure. Early IBM tape drives, such as the IBM727 and IBM729, were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long u-shaped loops of tape
8.
Reel
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A reel is an object around which lengths of another material are wound for storage. Generally a reel has a core and walls on the sides to retain the material wound around the core. In some cases the core is hollow, although other items may be mounted on it, the size of the core is dependent on several factors. A smaller core will obviously allow more material to be stored in a given space, however, there is a limit to how tightly the stored material can be wound without damaging it and this limits how small the core can be. Other issues affecting the core include, Mechanical strength of the core Acceptable turning speed any functional requirements of the core e. g. For a reel that must be mechanically turned the size of the grips that mount it on the mechanical turning device, the size of the mountings needed to support the core during unwinding. Anything mounted on the cores With material such as photographic film that is flat and long but is relatively wide, in cases where the material is more uniform in cross-section, the material may be safely wound around a reel that is wider than its width. In this case, several windings are needed to create a layer on the reel, most films have visible cues which mark the end of the reel. This allows projectionists running reel-to-reel to change over to the reel on the other projector. A so-called two-reeler would have run about 20–24 minutes since the short film shipped to a movie theater for exhibition may have had slightly less than 1,000 ft on it. Most modern projectionists use the term reel when referring to a 2, 000-foot two-reeler, as modern films are rarely shipped by single 1, a standard Hollywood movie averages about five 2000-foot reels in length. Had it not been standardized there would have many difficulties in the manufacture of the related equipment. A16 mm reel is 400 feet and it runs, at sound speed, approximately the same amount of time as a 1, 000-foot 35 mm reel. A split reel is a motion picture film reel in two halves that, when assembled, hold a specific length of motion picture film that has been wound on a plastic core. Using a split reel allows film to be shipped or handled in a lighter and smaller form than film would on a fixed reel, in silent film terminology, two films on one reel. Actors may submit a demo reel of their work to prospective employers, often in physical reel format
9.
Magnetic tape
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Magnetic tape is a medium for magnetic recording, made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany, based on magnetic wire recording, devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders. A device that stores data on magnetic tape is a tape drive. Magnetic tape revolutionized broadcast and recording, when all radio was live, it allowed programming to be recorded. At a time when gramophone records were recorded in one take, it allowed recordings to be made in multiple parts, which were then mixed and edited with tolerable loss in quality. It was a key technology in computer development, allowing unparalleled amounts of data to be mechanically created, stored for long periods. Nowadays, other technologies can perform the functions of magnetic tape, in many cases, these technologies are replacing tape. Despite this, innovation in the technology continues, and Sony, over years, magnetic tape made in the 1970s and 1980s can suffer from a type of deterioration called sticky-shed syndrome. Caused by hydrolysis of the binder of the tape, it can render the tape unusable, the oxide side of a tape is the surface that can be magnetically manipulated by a tape head. This is the side that stores the information, the side is simply a substrate to hold the tape together. The name originates from the fact that the side of most tapes is made of an oxide of iron. Magnetic tape was invented for recording sound by Fritz Pfleumer in 1928 in Germany, based on the invention of magnetic wire recording by Oberlin Smith in 1888, pfleumers invention used a ferric oxide powder coating on a long strip of paper. This invention was developed by the German electronics company AEG, which manufactured the recording machines and BASF. In 1933, working for AEG, Eduard Schuller developed the ring-shaped tape head, previous head designs were needle-shaped and tended to shred the tape. An important discovery made in this period was the technique of AC biasing, due to the escalating political tensions, and the outbreak of World War II, these developments were largely kept secret. A wide variety of recorders and formats have developed since, most significantly reel-to-reel, the practice of recording and editing audio using magnetic tape rapidly established itself as an obvious improvement over previous methods. Many saw the potential of making the same improvements in recording television, television signals are similar to audio signals. A major difference is that video signals use more bandwidth than audio signals, existing audio tape recorders could not practically capture a video signal
10.
Tape transport
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A tape transport is the collection of parts of a magnetic tape player or recorder that the actual tape passes through. Transport parts include the head, capstan, pinch roller, tape pins, the tape transport as a whole is called the transport mechanism. The capstan is a spindle used to move recording tape through the mechanism of a tape recorder. The capstan is always placed downstream from the tape heads, to maintain the required tension against the tape heads and other part of the tape transport, a small amount of drag is placed on the supply reel. Tape recorder capstans have a similar to nautical capstans, which however have no pinch rollers. The use of a capstan allows the tape to run at a precise, capstans are precision-machined spindles, and polished very smooth, any out-of-roundness or imperfections can cause uneven motion and an audible effect called flutter. The alternative to capstan drive, simply driving the tape takeup reel, dual capstans, where one is on each side of the heads, are claimed to provide even smoother tape travel across the heads and result in less variance in the recorded/playback signal. The pinch roller is a rubberized, free-spinning wheel typically used to press magnetic tape against a capstan shaft in order to create friction necessary to drive the tape along the magnetic heads. Most magnetic tape recorders use one capstan motor and one pinch roller located after the heads in the direction of the moving tape. However multiple pinch rollers may also be employed in association with one or more capstans, dual pinch rollers are also used in auto-reverse cassette decks to drive the tape in both directions as needed. In this case, only one pinch roller is pressed against its corresponding capstan at a time, a tension arm is a device used in magnetic tape recorders/reproducers to control the tension of the magnetic tape during machine operation. The recorders equipped with an arm can utilize more than one of them to control tape tension in different direction of winding or during different modes of tape operation. One of many US Patents pertaining to Tension arm Workbench Guide to Tape Recorder Servicing
