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105-501: There are many types of parallel ports, but the term has become most closely associated with the printer port or Centronics port found on most personal computers from the 1970s through the 2000s. It was an industry de facto standard for many years, and was finally standardized as IEEE 1284 in the late 1990s, which defined the Enhanced Parallel Port (EPP) and Extended Capability Port (ECP) bi-directional versions. Today,

210-524: A 19-inch rack . Many PDP-8s still operated decades later in these roles. De Castro was watching developments in manufacturing, especially more complex printed circuit boards (PCBs) and wave soldering that suggested that the PDP-8 could be produced much more inexpensively. DEC was not interested, having turned its attention increasingly to the high-end market. Convinced he could improve the process, De Castro began work on his own low-cost 16-bit design. The result

315-507: A legacy port and no longer include the parallel interface. Smaller machines have less room for large parallel port connectors. USB-to-parallel adapters are available that can make parallel-only printers work with USB-only systems. There are PCI (and PCI-express) cards that provide parallel ports. There are also some print servers that provide an interface to parallel ports through a network. USB-to-EPP chips can also allow other non-printer devices to continue to work on modern computers without

420-451: A 50 pin connector on the printer side—either a DD-50 (sometimes incorrectly referred to as a "DB50") or the block shaped M-50 connector; the M-50 was also referred to as Winchester. Dataproducts parallel was available in a short-line for connections up to 50 feet (15 m) and a long-line version using differential signaling for connections to 500 feet (150 m). The Dataproducts interface

525-480: A common assignment for the first logical parallel port (and therefore also for the corresponding LPT1 DOS device driver) today is 0x378, even though the default is still 0x3BC (and would be selected by the BIOS if it detects a printer port at this address). The IRQ lines are typically configurable in the hardware as well. Assigning the same interrupt to more than one printer port should be avoided and will typically cause one of

630-533: A decision, it was often cheaper for the users to simply throw out all of their existing machinery and buy a microcomputer product instead. If this was not the case at present, it certainly appeared it would be within a generation or two of Moore's law . In 1988, two company directors put together a report showing that if the company were to continue existing in the future, DG would have to either invest heavily in software to compete with new applications being delivered by IBM and DEC on their machines, or alternately exit

735-399: A fast toggle. Any of these issues might cause no or intermittent printing, missing or repeated characters or garbage printing. Some printer models may have a switch or setting to set busy by character; others may require a handshake adapter. Dataproducts introduced a very different implementation of the parallel interface for their printers. It used a DC-37 connector on the host side and

840-509: A few EMC webpages that only mentioned the latter company in passing, was sold to the Dollar General discount department store chain in October 2009. Data General exhibited a brash style of marketing and advertising, which acted to set the company in the spotlight. A memorable advertising campaign during the early 1980s Desktop Generation era, was issuance of T-shirts with the logo "We did it on

945-421: A host of other devices, have been designed to communicate with the system. An Wang , Robert Howard and Prentice Robinson began development of a low-cost printer at Centronics , a subsidiary of Wang Laboratories that produced specialty computer terminals . The printer used the dot matrix printing principle, with a print head consisting of a vertical row of seven metal pins connected to solenoids . When power

1050-480: A language runtime system implemented as a virtual machine which executed pre-compiled code as sequences of PLN statements and Eclipse commercial instruction routines. The latter provided microcode acceleration of arithmetic and conversion operations for a wide range of now-arcane data types such as overpunch characters. The DG Easy product, a portable application platform developed by Nichols and others from 1975 to 1979 but never marketed, had roots easily traceable back to

1155-476: A large niche for Unix storage systems, and its sales were still strong enough to make DG a takeover target. EMC , the 800-pound gorilla in the storage market, announced in August 1999 that they would buy Data General and its assets for $ 1.1 billion or $ 19.58 a share. The acquisition was completed on October 12, 1999. Although details of the acquisition specified that EMC had to take the entire company, and not just

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1260-404: A more powerful machine, it was often cheaper to buy another from the same company. This was known as " vendor lock-in ", which helped guarantee future sales, even though the customers detested it. With the change in software development, combined with new generations of commodity processors that could match the performance of low-end minicomputers, lock-in was no longer working. When forced to make

1365-504: A multi-user platform far ahead of many contemporary systems. A series of updated Nova machines were released through the early 1970s that kept the Nova line at the front of the 16-bit mini world. The Nova was followed by the Eclipse series which offered much larger memory capacity while still being able to run Nova code without modification. The Eclipse launch was marred by production problems and it

1470-443: A parallel port. For electronics hobbyists the parallel port is still often the easiest way to connect to an external circuit board. It is faster than the other common legacy port (serial port), requires no serial-to-parallel converter, and requires far less interface logic and software than a USB target interface. However, Microsoft operating systems later than Windows 95/98 prevent user programs from directly writing to or reading from

1575-401: A process is run as root and an ioperm() command is used to allow access to its base address ; alternatively, ppdev allows shared access and can be used from userspace if the appropriate permissions are set. The cross-platform library for parallel port access, libieee1284, also is available on many Linux distributions and provides an abstract interface to the parallel ports of the system. Access

1680-719: A single system. Following AViiON was the CLARiiON series of network-attached storage systems which became a major product line in the later 1990s. This led to a purchase by EMC , the major vendor in the storage space at that time. EMC shut down all of DG's lines except for CLARiiON, which continued sales until 2012. Data General (DG) was founded by several engineers from Digital Equipment Corporation who were frustrated with DEC's management and left to form their own company. The chief founders were Edson de Castro , Henry Burkhardt III, and Richard Sogge of Digital Equipment (DEC), and Herbert Richman of Fairchild Semiconductor . The company

1785-550: A small range of tasks. For instance, IBM often delivered machines whose only purpose was to generate accounting data for a single company, running software tailored for that company alone. By the mid-1980s, the introduction of new software development methods and the rapid acceptance of the SQL database was changing the way such software was developed. Now developers typically linked together several pieces of existing software, as opposed to developing everything from scratch. In this market,

1890-470: A standard by market forces and competition , in a two-sided market , after a dispute . Examples: An example of an ongoing dispute is OASIS 's OpenDocument format vs Microsoft's Office Open XML format. Data General Data General Corporation was one of the first minicomputer firms of the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation (DEC). Their first product, 1969's Data General Nova ,

1995-400: A standard required by law (also known as de jure standards ). Joint technical committee on information technology (ISO/IEC JTC1) developed a procedure in order for de facto standards to be processed through the formal standardization system to be transformed into international standards from ISO and IEC . In social sciences a voluntary standard that is also a de facto standard is

2100-409: A typical solution to a coordination problem . The choice of a de facto standard tends to be stable in situations in which all parties can realize mutual gains, but only by making mutually consistent decisions. In contrast, an enforced de jure standard is a solution to the prisoner's problem . Examples of some well known de facto standards: There are many examples of de facto consolidation of

2205-423: Is a custom or convention that is commonly used even though its use is not required. De facto is a Latin phrase (literally " of fact "), here meaning "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established". A de facto standard contrasts an international standard which is defined by an organization such as International Standards Organization , or

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2310-487: Is handled in an open-claim-release-close sequence, which allows for concurrent access in userspace. The older parallel printer ports had an 8-bit data bus and four pins for control output (Strobe, Linefeed, Initialize, and Select In), and five more for control input (ACK, Busy, Select, Error, and Paper Out). Its data transfer speed is at 150 kB/s. It is possible for a parallel port to have a speed of 300 KB/s. The newer EPPs (Enhanced Parallel Ports) have an 8-bit data bus, and

2415-611: Is now popularly known as the " Centronics connector ". The Centronics Model 101 printer, featuring this connector, was released in 1970. The host sent ASCII characters to the printer using seven of eight data pins, pulling them high to +5V to represent a 1. When the data was ready, the host pulled the STROBE pin low, to 0 V. The printer responded by pulling the BUSY line high, printing the character, and then returning BUSY to low again. The host could then send another character. Control characters in

2520-434: Is present at 0x3BC, the second port in the row (0x378) becomes logical parallel port 1 and 0x278 becomes logical parallel port 2 for the BIOS. Sometimes, printer ports are jumpered to share an interrupt despite having their own IO addresses (i.e. only one can be used interrupt-driven at a time). In some cases, the BIOS supports a fourth printer port as well, but the base address for it differs significantly between vendors. Since

2625-522: Is similar to IBM's byte mode in concept, but changes details of the handshaking to allow up to 2 MB/s. The Extended Capability Port (ECP) is essentially an entirely new port in the same physical housing that also adds direct memory access based on ISA and run-length encoding to compress the data, which is especially useful when transferring simple images like faxes or black-and-white scanned images. ECP offers performance up to 2.5 MB/s in both directions. All of these enhancements are collected as part of

2730-489: The Data General/One (DG-1) in 1984 is one of the few cases of a minicomputer company introducing a truly breakthrough PC product. Considered genuinely portable, rather than "luggable", as alternatives often were called, it was a nine-pound battery-powered MS-DOS machine equipped with dual 3 1 ⁄ 2 -inch diskettes, a 79-key full-stroke keyboard, 128 KB to 512 KB of RAM, and a monochrome LCD screen capable of either

2835-527: The IEEE 1284 standard. The first release in 1994 included original Centronics mode ("compatibility mode"), nibble and byte modes, as well as a change to the handshaking that was already widely used; the original Centronics implementation called for the BUSY lead to toggle with each change on any line of data (busy-by-line), whereas IEEE 1284 calls for BUSY to toggle with each received character (busy-by-character). This reduces

2940-506: The Motorola 88000 RISC processor. The AViiON machines supported multi-processing, later evolving into NUMA -based systems, allowing the machines to scale upwards in performance by adding additional processors. An important element in all enterprise computer systems is high speed storage. At the time AViiON came to market, commodity hard disk drives could not offer the sort of performance needed for data center use. DG attacked this problem in

3045-593: The Open Systems Interconnection (OSI) protocol suite . Data General produced a full range of peripherals, sometimes by rebadging printers for example, but Data General's own series of CRT-based and hard-copy terminals were high quality and featured a generous number of function keys, each with the ability to send different codes, with any combination of control and shift keys, which influenced WordPerfect design. The model 6053 Dasher 2 featured an easily tilted screen, but used many integrated circuits ;

3150-501: The Xerox Alto . In 1974, the Nova was supplanted by their upscale 16-bit machine, the Eclipse . Based on many of the same concepts as the Nova, it included support for virtual memory and multitasking more suitable to the small office environment. For this reason, the Eclipse was packaged differently, in a floor-standing case resembling a small refrigerator . Production problems with

3255-446: The "A" models used a print head with 9 pins and formed glyphs that were 9 by 7. This left the problem of sending the ASCII data to the printer. While a serial port does so with the minimum of pins and wires, it requires the device to buffer up the data as it arrives bit by bit and turn it back into multi-bit values. A parallel port makes this simpler; the entire ASCII value is presented on

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3360-600: The Centronics interface— only IBM logo printers ( rebranded from Epson ) could be used with the IBM PC. IBM standardized the parallel cable with a DB25F connector on the PC side and the 36-pin Centronics connector on the printer side. Vendors soon released printers compatible with both standard Centronics and the IBM implementation. The original IBM parallel printer adapter for the IBM PC of 1981

3465-464: The DG One Portable. Some software development from the early 1970s is notable. PLN (created by Robert Nichols) was the host language for a number of DG products, making them easier to develop, enhance, and maintain than macro assembler equivalents. PLN smacked of a micro-subset of PL/I , in sharp contrast to other languages of the time, such as BLISS . The RPG product (shipped in 1976) incorporated

3570-510: The DG factory in Mexico where they were made and refurbished. In retrospect, the nicely performing MV series was too little, too late. At a time when DG invested its last dollar into the dying minicomputer segment, the microcomputer was rapidly making inroads to the lower-end market segment, and the introduction of the first workstations wiped out all 16-bit machines, once DG's best customer segment. While

3675-547: The Desktop Generation range also struggled, partly because they offered an economical way of running what was essentially "legacy software" while the future was clearly either slightly cheaper Personal Computers or slightly more expensive "super minicomputers" such as the MV and VAX computers. Throughout the 1980s, the computer market had evolved dramatically. Large installations in the past typically ran custom-developed software for

3780-416: The Eclipse led to a rash of lawsuits in the late 1970s. Newer versions of the machine were pre-ordered by many of DG's customers, which were never delivered. Many customers sued Data General after more than a year of waiting, charging the company with breach of contract , while others simply canceled their orders and went elsewhere. The Eclipse was originally intended to replace the Nova outright, evidenced by

3885-613: The Eclipse MV line, and a modified version of UNIX System V called DG/UX for the Eclipse MV and AViiON machines. The AOS/VS software was the most commonly used DG software product and included CLI (Command Line Interpreter) allowing for complex scripting, DUMP/LOAD, and other custom components. Related system software also in common use at the time included such packages as X.25 , Xodiac, and TCP/IP for networking, Fortran , COBOL , RPG , PL/I , C and Data General Business Basic for programming, INFOS II and DG/DBMS for databases, and

3990-449: The LPT without additional software (kernel extensions). Older CNC Milling Machines also often make use of the parallel port to directly control the machine's motors and attachments. Traditionally IBM PC systems have allocated their first three parallel ports according to the configuration in the table below (if all three printer ports exist). If there is an unused slot, the port addresses of

4095-448: The MV series did stop the erosion of DG's customer base, this now smaller base was no longer large enough to allow DG to develop their next generation. DG had also changed their marketing to focus on direct sales to Fortune 100 companies and thus alienated many resellers. Data General developed operating systems for its hardware: DOS and RDOS for the Nova, RDOS and AOS for the 16-bit Eclipse C, M, and S lines, AOS/VS and AOS/VS II for

4200-570: The MV/2000 (later MV/2500), MV/4000, MV/10000, MV/15000, MV/20000, MV/30000, MV/40000 and ultimately concluded with the MV/60000HA minicomputer. The MV/60000HA was intended to be a High Availability system, with many components duplicated to eliminate the single point of failure. Yet, there were failures among the system's many daughter boards, back-plane, and mid-plane. DG technicians were kept quite busy replacing boards and many blamed poor quality control at

4305-402: The Nova generated 20% annual growth rates for the company, becoming a star in the business community and generating US$ 100 million in sales in 1975. In 1977, DG launched a 16-bit microcomputer called the microNOVA to poor commercial success. The Nova series played a very important role as instruction-set inspiration to Charles P. Thacker and others at Xerox PARC during their construction of

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4410-464: The PC-end of the interface, creating the now familiar parallel cable with a DB25M at one end and a 36-pin micro ribbon connector at the other. In theory, the Centronics port could transfer data as rapidly as 75,000 characters per second. This was far faster than the printer, which averaged about 160 characters per second, meaning the port spent much of its time idle. The performance was defined by how rapidly

4515-459: The RPG VM created by Stephen Schleimer. Also notable were several commercial software products developed in the mid to late 1970s in conjunction with the commercial computers. These products were popular with business customers because of their screen design feature and other ease-of-use features. The original IDEA ran on RDOS and would support up to 24 users in an RDOS Partition. Each user could use

4620-647: The aging of DEC's 16-bit products, notably the PDP-11 , which were coming due for replacement. It appeared there was an enormous potential market for 32-bit machines, one that DG might be able to "scoop". Data General immediately launched their own 32-bit effort in 1976 to build what they called the "world's best 32-bit machine", known internally as the "Fountainhead Project", or FHP for short (Fountain Head Project). Development took place off-site so that even DG workers would not know of it. The developers were given free rein over

4725-486: The best "commodity" machines instead. "Specifically", the report stated, "DG should examine the Unix market, where all of the needed software already exists, and see if DG can provide compelling Unix solutions." Now the customer could run any software they wished as long as it ran on Unix, and by the early 1990s, everything did. As long as DG's machines outperformed the competition, their customers would return, because they liked

4830-541: The bi-directional system, allowing various status report information to be sent. Before the advent of USB , the parallel interface was adapted to access a number of peripheral devices other than printers. One early use of the parallel port was for dongles used as hardware keys which were supplied with application software as a form of software copy protection. Other uses included optical disc drives such as CD readers and writers, Zip drives , scanners , tape drives , external modems , gamepads , and joysticks . Some of

4935-520: The computer to crash if the user types "C:\CON\CON", "C:\PRN\PRN" or "C:\AUX\AUX" in the Windows Explorer address bar or via the Run command. Microsoft has since released a patch to fix this issue, however fresh installs of Windows 95 and 98 are not patched with this fix and will still have this issue. A special " PRINT " command also existed to achieve the same effect. Microsoft Windows still refers to

5040-582: The corresponding ports to work in polled mode only. The port addresses assigned to slot can be determined by reading the BIOS Data Area (BDA) at 0000h:0408h. Bit-to-pin mapping for the Standard Parallel Port (SPP): ~ indicates a hardware inversion of the bit. In versions of Windows that did not use the Windows NT kernel (as well as DOS and some other operating systems), programs could access

5145-574: The data caused other actions, like the CR or EOF . The host could also have the printer automatically start a new line by pulling the AUTOFEED line high, and keeping it there. The host had to carefully watch the BUSY line to ensure it did not feed data to the printer too rapidly, especially given variable-time operations like a paper feed. The printer side of the interface quickly became an industry de facto standard , but manufacturers used various connectors on

5250-525: The design and selected a system that used a writable instruction set. The idea was that the instruction set architecture (ISA) was not fixed, programs could write their own ISA and upload it as microcode to the processor's writable control store . This would allow the ISA to be tailored to the programs being run, for instance, one might upload an ISA tuned for COBOL if the company's workload included significant numbers of COBOL programs. When Digital's VAX-11/780

5355-425: The earliest portable MP3 players required a parallel port connection for transferring songs to the device. Adapters were available to run SCSI devices via parallel. Other devices such as EPROM programmers and hardware controllers could be connected via the parallel port. Most PC-compatible systems in the 1980s and 1990s had one to three ports, with communication interfaces defined like this: If no printer port

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5460-480: The end of the decade, the entire market had largely disappeared. The introduction of the Data General/One in 1984 did nothing to stop the erosion. In a major business pivot, in 1989 DG released the AViiON series of scalable Unix systems which spanned from desktop workstations to departmental servers . This scalability was managed through the use of NUMA , allowing a number of commodity processors to work together in

5565-534: The existing port's relatively few status pins. While the IBM solution could support this, it was not trivial to implement and was not at that time being supported. This led to the Bi-Tronics system, introduced by HP on their LaserJet 4Si in April 1993. This used four existing status pins, ERROR, SELECT, PE and BUSY to represent a nibble , using two transfers to send an 8-bit value. Bi-Tronics mode, now known as nibble mode,

5670-527: The explosion of the internet in the latter 1990s with the formation of the THiiN Line business unit, led by Tom West, which had a focus on creation and sale of so-called "internet appliances". The product developed was called the SiteStak web server appliance and was designed as an inexpensive website hosting product. CLARiiON was the only product line that saw continued success through the later 1990s after finding

5775-521: The fact that the Nova 3 series, released at the same time and utilizing virtually the same internal architecture as the Eclipse, was phased out the next year. Strong demand continued for the Nova series, resulting in the Nova 4, perhaps as a result of the continuing problems with the Eclipse. While DG was still struggling with Eclipse, in 1977, Digital announced the VAX series, their first 32-bit minicomputer line, described as " super-minis ". This coincided with

5880-489: The first joint venture between an American computer company and a Soviet company. DG would provide hardware and NPO Parma the software, and Austrian companies Voest Alpine Industrieanlagenbau and their marketing group Voest Alpine Vertriebe would build the plant. Despite Data General's betting the AViiON farm on the Motorola 88000 , Motorola decided to end production of that CPU. The 88000 had never been very successful, and DG

5985-491: The full-sized standard 80×25 characters or full CGA graphics (640×200). The DG-1 was considered a modest advance over similar Osborne / Kaypro systems overall. Data General also brought out a small-footprint "Desktop Generation" range, starting with the DG10 that included both Data General and Intel CPUs in a patented closely coupled arrangement, able to run MS-DOS or CP/M-86 concurrently with DG/RDOS, with each benefiting from

6090-446: The hardware acceleration given by other CPU as a co-processor that would handle (for instance) screen graphics or disk operations concurrently. Other members of the Desktop Generation range, the DG20 and DG30, were aimed more at traditional commercial environments, such as multi-user COBOL systems, replacing refrigerator-sized minicomputers with toaster-sized modular microcomputers based around

6195-408: The hardware. Years later, in 1987, IBM reintroduced the bidirectional interface with its IBM PS/2 series, where it could be enabled or disabled for compatibility with applications hardwired not to expect a printer port to be bidirectional. As the printer market expanded, new types of printing mechanisms appeared. These often supported new features and error conditions that could not be represented on

6300-413: The host could respond to the printer's BUSY signal asking for more data. To improve performance, printers began incorporating buffers so the host could send them data more rapidly, in bursts. This not only reduced (or eliminated) delays due to latency waiting for the next character to arrive from the host, but also freed the host to perform other operations without causing a loss of performance. Performance

6405-469: The initial success of the Nova, Data General went public in the fall of 1969. The original Nova was soon followed by the faster SuperNova, which replaced the Nova's 4-bit arithmetic logic unit (ALU) with a 16-bit version that made the machine roughly four times as fast. Several variations and upgrades to the SuperNova core followed. The last major version, the Nova 4, was released in 1978. During this period

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6510-470: The logical parallel ports detected by the BIOS available under device names such as LPT1 , LPT2 or LPT3 (corresponding with logical parallel port 1, 2, and 3, respectively). These names derive from terms like Line Print Terminal , Local Print Terminal (both abbreviated as LPT ), or Line Printer. A similar naming convention was used on ITS , DEC systems, as well as in CP/M and 86-DOS ( LST ). In DOS ,

6615-433: The machines, not because they were forced; lock-in was over. De Castro agreed with the report, and future generations of the MV series were terminated. Instead, DG released a technically interesting series of Unix servers known as the AViiON . The name "AViiON" was a reversed play on the name of DG's first product, Nova, implying "Nova II". In an effort to keep costs down, the AViiON was originally designed and shipped with

6720-530: The mapping internally via a CONFIG.SYS PRN =n directive (as under DR-DOS 7.02 and higher). DR-DOS 7.02 also provides optional built-in support for LPT4 if the underlying BIOS supports it. PRN, along with CON, AUX and a few others are invalid file and directory names in DOS and Windows, even on Windows XP and later. This set of invalid file and directory names also affects Windows 95 and 98 , which had an MS-DOS device in path name vulnerability in which it causes

6825-512: The meantime, customers were abandoning Data General in droves, driven not only by the delivery problems with the original Eclipse, including very serious quality control and customer service problems, but also the power and versatility of Digital's new VAX line. Ultimately, Fountainhead was cancelled and Eagle became the new MV series, with the first model, the Data General Eclipse MV/8000 , announced in April 1980. The Eagle Project

6930-529: The microECLIPSE CPUs and some of the technology developed for the microNOVA-based "Micro Products" range such as the MP/100 and MP/200 that had struggled to find a market niche. The Single-processor version of the DG10, the DG10SP, was the entry-level machine with, like the DG20 and 30, no ability to run Intel software. Despite having some good features and having less direct competition from the flood of cheap PC compatibles,

7035-418: The nascent relational database software DG/SQL . Data General also offered an office automation suite named Comprehensive Electronic Office (CEO), which included a mail system, a calendar, a folder-based document store, a word processor (CEOWrite), a spreadsheet processor, and other assorted tools. All were crude by today's standards, but were revolutionary for their time. CEOWrite was also offered on

7140-455: The number of BUSY toggles and the resulting interruptions on both sides. A 1997 update standardized the printer status codes. In 2000, the EPP and ECP modes were moved into the standard, as well as several connector and cable styles, and a method for daisy chaining up to eight devices from a single port. Some host systems or print servers may use a strobe signal with a relatively low voltage output or

7245-422: The others are moved up. (For example, if a port at 0x3BC does not exist, the port at 0x378 will then become the first logical parallel port.) The base address 0x3BC is typically supported by printer ports on MDA and Hercules display adapters, whereas printer ports provided by the mainboard chipset or add-on cards rarely allow to be configured to this base address. Therefore, in absence of a monochrome display adapter,

7350-599: The parallel port interface is virtually non-existent in new computers because of the rise of Universal Serial Bus (USB) devices, along with network printing using Ethernet and Wi-Fi connected printers. The parallel port interface was originally known as the Parallel Printer Adapter on IBM PC-compatible computers. It was primarily designed to operate printers that used IBM's eight-bit extended ASCII character set to print text, but could also be used to adapt other peripherals. Graphical printers, along with

7455-425: The parallel port with simple outportb() and inportb() subroutine commands. In operating systems such as Windows NT and Unix ( NetBSD , FreeBSD , Solaris , 386BSD , etc.), the microprocessor is operated in a different security ring, and access to the parallel port is prohibited, unless using the required driver. This improves security and arbitration of device contention. On Linux, inb() and outb() can be used when

7560-507: The parallel printers could be accessed directly on the command line . For example, the command " TYPE C:\AUTOEXEC.BAT > LPT1: " would redirect the contents of the AUTOEXEC.BAT file to the printer port. A PRN device was also available as an alias for LPT1. Some operating systems (like Multiuser DOS ) allow to change this fixed assignment by different means. Some DOS versions use resident driver extensions provided by MODE, or users can change

7665-447: The pins in complete form. In addition to the eight data pins, the system also needed various control pins as well as electrical grounds. Wang happened to have a surplus stock of 20,000 Amphenol 36-pin micro ribbon connectors that were originally used for one of their early calculators. The interface only required 21 of these pins, the rest were grounded or not connected. The connector has become so closely associated with Centronics that it

7770-405: The pins used for data transfer back to the host were already printer-to-host lines. The introduction of new devices like scanners and multi-function printers demanded much more performance than either the Bi-Tronics or IBM style backchannels could handle. Two other standards have become more popular for these purposes. The Enhanced Parallel Port (EPP), originally defined by Zenith Electronics ,

7875-464: The ports in this manner in many cases, though this is often fairly hidden. In SCO UNIX and Linux , the first parallel port is available via the filesystem as /dev/lp0 . Linux IDE devices can use a paride (parallel port IDE) driver. For consumers, USB and computer networks have replaced the parallel printer port, for connections both to printers and to other devices. Many manufacturers of personal computers and laptops consider parallel to be

7980-399: The proprietary hardware business entirely. Thomas West 's report outlined these changes in the marketplace, and suggested that the customer was going to win the fight over lock-in. They also outlined a different solution: Instead of trying to compete against the much larger IBM and DEC, they suggested that since the user no longer cared about the hardware as much as software, DG could deliver

8085-412: The question of which machine was the "best" changed; it was no longer the machine with the best price–performance ratio or service contracts, but the one that ran all of the third-party software the customer intended to use. This change forced changes on the hardware vendors as well. Formerly, almost all computer companies attempted to make their machines different enough that when their customers sought

8190-448: The rapid commoditization of the Unix market led to shrinking sales. DG did begin a minor shift toward the service industry, training their technicians for the role of implementing a spate of new x86-based servers and the new Microsoft Windows NT domain-driven, small server world. This never developed enough to offset the loss of high margin server business however. Data General also targeted

8295-451: The reserved entry for a fourth logical printer port in the BIOS Data Area (BDA) is shared with other uses on PS/2 machines and with S3 compatible graphics cards, it typically requires special drivers in most environments. Under DR-DOS 7.02 the BIOS port assignments can be changed and overridden using the LPT1 , LPT2 , LPT3 (and optionally LPT4 ) CONFIG.SYS directives. DOS-based systems make

8400-447: The same control pins as the normal parallel printer port. Newer ports reach speeds of up to 2 MB/s. Pinouts for parallel port connectors are: Inverted lines are true on logic low. If they are not inverted, then logic high is true. Pin 25 on the DB25 connector might not be connected to ground on modern computers. Hardware IC chips: De facto standard A de facto standard

8505-543: The same fashion as the processor issue, by running a large number of drives in parallel. The overall performance was greatly improved and the resulting innovation was marketed originally as the HADA (High Availability Disk Array) and then later as the CLARiiON line. The CLARiiON arrays, which offered SCSI RAID in various capacities, offered a great price/performance and platform flexibility over competing solutions. The CLARiiON line

8610-451: The same or a different program. Eventually, IDEA ran on every commercial hardware product from the MicroNova (4 users) to the MV series under AOS/VS, the same IDEA program running all those systems. The CS40 (the first of this line) was a package system which supported four terminal users, each running a different COBOL program. In 1979, DG introduced their Xodiac networking system. This

8715-697: The smaller, lighter D100, D200 and eventually the D210 replaced it as the basic user terminal, while graphics models such as the D460 (with ANSI X3.64 compatibility) occupied the very high end of the range. Terminal emulators for the D2/D3/D100/D200/D210 (and some features of the D450/460) do exist, including the Freeware 1993 DOS program in D460.zip. Most Data General software was written specifically for their own terminals (or

8820-441: The storage line, EMC quickly ended all development and production of DG computer hardware and parts, effectively ending Data General's presence in the segment. The maintenance business was sold to a third party, who also acquired all of DG's remaining hardware components for spare parts sales to old DG customers. The CLARiiON line continued to be a major player in the market and was marketed under that name until January 2012. CLARiiON

8925-500: The system side, so a variety of cables were required. For example, NCR used the 36-pin micro ribbon connector on both ends of the connection, early VAX systems used a DC-37 connector, Texas Instruments used a 25-pin card edge connector and Data General used a 50-pin micro ribbon connector. When IBM implemented the parallel interface on the IBM PC , they used the DB-25F connector at

9030-526: The terminal emulation built into the Desktop Generation DG10, but the Data General One built-in terminal emulator is not often suitable), although software using Data General Business BASIC could be more flexible in terminal handling, because logging into a Business BASIC system would initiate a process whereby the terminal type would (usually) be auto-detected. Data General's introduction of

9135-425: Was a 16-bit minicomputer intended to both outperform and cost less than the equivalent from DEC, the 12-bit PDP-8 . A basic Nova system cost two-thirds or less than a similar PDP-8 while running faster, offering easy expandability, being significantly smaller, and proving more reliable in the field. Combined with Data General RDOS (DG/RDOS) and programming languages like Data General Business Basic , Novas provided

9240-536: Was a straightforward, 32-bit extension of the Nova-based Eclipse. It was backwards-compatible with 16-bit Eclipse applications, used the same command-line interpreter, but offered improved 32-bit performance over the VAX 11/780 while using fewer components. By late 1979, it became clear that Eagle would deliver before Fountainhead, igniting an intense turf war within the company for constantly shrinking project funds. In

9345-545: Was also widely sold by Dell through a worldwide OEM deal with EMC. The Clariion and Celerra storage products evolved into EMC's unified storage platform, the VNX platform. Data General would be only one of many New England based computer companies, including the original Digital Equipment Corporation , that collapsed or were sold to larger companies after the 1980s. On the Internet, even the old Data General domain (dg.com), which contained

9450-408: Was applied to the solenoids, the pin was pushed forward to strike the paper and leave a dot. To make a complete character glyph , the print head would receive power to specified pins to create a single vertical pattern, then the print head would move to the right by a small amount, and the process repeated. On their original design, a typical glyph was printed as a matrix seven high and five wide, while

9555-524: Was based on the X.25 standard at the lower levels, and their own application layer protocols on top. Because it was based on X.25, remote sites could be linked together over commercial X.25 services like Telenet in the US or Datapac in Canada. Data General software packages supporting Xodiac included Comprehensive Electronic Office (CEO). In June 1987, Data General announced its intention to replace Xodiac with

9660-417: Was designed to support limited bidirectionality, with 8 lines of data output and 4 lines of data input. This allowed the port to be used for other purposes, not just output to a printer. This was accomplished by allowing the data lines to be written to by devices on either end of the cable, which required the ports on the host to be bidirectional. This feature saw little use, and was removed in later revisions of

9765-505: Was found on many mainframe systems up through the 1990s, and many printer manufacturers offered the Dataproducts interface as an option. A wide variety of devices were eventually designed to operate on a parallel port. Most devices were uni-directional (one-way) devices, only meant to respond to information sent from the PC. However, some devices such as Zip drives were able to operate in bi-directional mode. Printers also eventually took up

9870-512: Was founded in Hudson, Massachusetts , in 1968. Harvey Newquist was hired from Computer Control Corporation to oversee manufacturing. Edson de Castro was the chief engineer in charge of the PDP-8 , DEC's line of inexpensive computers that created the minicomputer market. It was designed specifically to be used in laboratory equipment settings; as the technology improved, it was reduced in size to fit into

9975-466: Was further improved by using the buffer to store several lines and then printing in both directions, eliminating the delay while the print head returned to the left side of the page. Such changes more than doubled the performance of an otherwise unchanged printer, as was the case on Centronics models like the 102 and 308. IBM released the IBM Personal Computer in 1981 and included a variant of

10080-509: Was indicated by the host pulling the SELECT line high, and data was transferred when the host toggles the AUTOFEED low. Other changes in the handshaking protocols improved performance, reaching 400,000 cps to the printer, and about 50,000 cps back to the host. A major advantage of the Bi-Tronics system is that it can be driven entirely in software in the host, and uses otherwise unmodified hardware - all

10185-505: Was marketed not only to AViiON and Data General MV series customers, but also to customers running servers from other vendors such as Sun Microsystems , Hewlett-Packard and Silicon Graphics . Data General also embarked on a plan to hire storage sales specialists and to challenge the EMC Symmetrix in the wider market. On December 12, 1989, DG and Soviet Union software developer NPO Parma announced Perekat (Перекат, “Rolling Thunder,”)

10290-414: Was packaged on four PCB cards and was thus smaller in height, while also including a number of features that made it run considerably faster. Announced as "the best small computer in the world", the Nova quickly gained a following, especially in scientific and educational markets, and made the company flush with cash. DEC sued for misappropriation of its trade secrets, but this ultimately went nowhere. With

10395-507: Was released in 1969 by Data General as the Nova . The Nova, like the PDP-8, used a simple accumulator-based architecture . It lacked general registers and the stack-pointer functionality of the more advanced PDP-11 , as did competing products, such as the HP 1000 ; compilers used hardware-based memory locations in lieu of a stack pointer. Designed to be rack-mounted similarly to the later PDP-8 machines, it

10500-559: Was shipped in February 1978, however, Fountainhead was not yet ready to deliver a machine, due mainly to problems in project management. DG's customers left quickly for the VAX world. In the spring of 1978, with Fountainhead apparently in development hell , a secret skunkworks project was started to develop an alternative 32-bit system known as "Eagle" by a team led by Tom West . References to "the Eagle project" and "Project Eagle" co-exist. Eagle

10605-430: Was some time before it was a reliable replacement for the tens of thousands of Novas in the market. As the mini world moved from 16-bit to 32, DG introduced the Data General Eclipse MV/8000 , whose development was extensively documented in the popular book, The Soul of a New Machine . Although DG's computers were successful, the introduction of the IBM PC in 1981 marked the beginning of the end for minicomputers, and by

10710-550: Was the United States Forest Service , which starting in the mid-1980s used DG systems installed at all levels from headquarters in Washington, D.C. down to individual ranger stations and fire command posts. This required equipment of high reliability and generally rugged construction that could be deployed in a wide range of places, often to be maintained and used by people with no computer background at all. The intent

10815-599: Was the only major customer. When Apple Computer and IBM proposed their joint solution based on POWER architecture , the PowerPC , Motorola picked up the manufacturing contract and killed the 88000. DG quickly responded by introduced new models of the AViiON series based on a true commodity processor, the Intel x86 series. By this time a number of other vendors, notably Sequent Computer Systems , were also introducing similar machines. The lack of lock-in now came back to haunt DG, and

10920-417: Was the subject of Tracy Kidder 's Pulitzer prize -winning book, The Soul of a New Machine , making the MV line the best-documented computer project in recent history. The MV systems generated an almost miraculous turnaround for Data General. Through the early 1980s sales picked up, and by 1984 the company had over a billion dollars in annual sales. One of Data General's significant customers at this time

11025-554: Was to create new kinds of functional integration in an agency that had long prized its decentralized structure. Despite some tensions, the implementation was effective and the overall effects on the agency notably positive. The introduction, implementation, and effects of the DG systems in USFS were documented in a series of evaluative reports prepared in the late 1980s by the RAND Corporation . The MV series came in various iterations, from

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