Hey All, Trying to connect to the Power5 9133-55A serial console using a serial-to-usb converter (RS232). The other end is connected via null modem. Tried minicom, putty and other Linux utilities, no The UNIX and Linux Forums.
A connector often used for a parallel printer port on computers, with the printer icon.TypePoint-to-pointProduction historyDesigner,Designed1970-1981ManufacturerCentronics, Dataproducts, Intel, IBM, Compaq, Nortel, etcSuperseded by(1996)General specificationsLength2.3 cm (0.91 in)Hot pluggableUsually notExternalYesCableUsually up to 25 wires including ground; optionally shieldedPins8 data, 4 output control, 5 input control, 8 groundConnector, othersElectricalSignal0 to +5.0 voltMax. Voltage5 volts DCDataData signalWidthVariableBitratePP: 150,EPP: 2 /sECP: 2.5 MB/sMax.
Devices2ProtocolApplication dependentPin outIBM PC-compatible parallel port pinout. The Apple II Parallel Printer Port connected to the printer via a folded ribbon cable; one end connected to the connector at the top of the card, and the other end had a 36-pin Centronics connector.A parallel port is a type of found on ( and otherwise) for connecting peripherals. Tv serial malayalam. The name refers to the way the data is sent; parallel ports send multiple of data at once, in, as opposed to that send bits one at a time. To do this, parallel ports require multiple data lines in their cables and port connectors, and tend to be larger than contemporary serial ports which only require one data line.There are many types of parallel ports, but the term has become most closely associated with the printer port or found on most from the 1970s through the 2000s. It was an industry for many years, and was finally standardized as in the late 1990s, which defined the and bi-directional versions. Today, the parallel port interface is virtually non-existent because of the rise of (USB) devices, along with network printing using and connected printers.The parallel port interface was originally known as the Parallel Printer Adapter on.
It was primarily designed to operate that used 's eight-bit to print text, but could also be used to adapt other peripherals. Graphical printers, along with a host of other devices, have been designed to communicate with the system. Contents.History Centronics , Robert Howard and Prentice Robinson began development of a low-cost printer at, a subsidiary of that produced specialty. The printer used the principle, with a print head consisting of a vertical row of seven metal pins connected to.
When power was applied to the solenoids, the pin was pulled forward to strike the paper and leave a dot. To make a complete character, 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 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 data to the printer. While a 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 the pins in complete form. In addition to the seven data pins, the system also needed various control pins as well as electrical grounds.
Wang happened to have a surplus stock of 20,000 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 is now popularly known as the 'Centronics connector'.The 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 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, but manufacturers used various connectors on the system side, so a variety of cables were required. For example, used the 36-pin connector on both ends of the connection, early systems used a connector, used a 25-pin card and used a 50-pin micro ribbon connector. When implemented the parallel interface on the, they used the connector at 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 the host could respond to the printer's BUSY signal asking for more data. To improve performance, printers began incorporating 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 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 in 1981 and included a variant of the Centronics interface— only IBM logo printers ( from ) could be used with the IBM PC. IBM standardized the parallel cable with a 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 was designed to support 8-bit data bidirectionally in 1981. 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 the hardware. Years later, in 1987, IBM reintroduced the bidirectional interface with its series, where it could be enabled or disabled for compatibility with applications hardwired not to expect a printer port to be bidirectional.Bi-Tronics 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 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 on their in 1992. This used four existing status pins, ERROR, SELECT, PE and BUSY to represent a, using two transfers to send an 8-bit value.
Bi-Tronics mode, now known as nibble mode, 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 the pins used for data transfer back to the host were already printer-to-host lines.EPP and ECP The introduction of new devices like and 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, is similar to IBM's byte mode in concept, but changes details of the handshaking to allow up to 2 MByte/s.
The Extended Capability Port (ECP) is essentially an entirely new port in the same physical housing that also adds based on and to compress the data, which is especially useful when transferring simple images like or black-and-white scanned images. ECP offers performance up to 2.5 MByte/s in both directions.All of these enhancements are collected as part of the 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 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 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 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 connector on the host side and a 50 pin connector on the printer side—either a (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 for connections to 500 feet (150 m). The Dataproducts interface 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 were able to operate in bi-directional mode. Printers also eventually took up the bi-directional system, allowing various status report information to be sent.Historical uses. C4381A CD-Writer Plus 7200 Series, showing parallel ports to connect between a printer and the computer.Before the advent of, the parallel interface was adapted to access a number of peripheral devices other than printers. One early use of the parallel port was for used as hardware keys which were supplied with application software as a form of software copy protection.
Other uses included such as readers and writers, external,. Some of the earliest portable required a parallel port connection for transferring songs to the device.
Adapters were available to run devices via parallel. Etherpocket-SP parallel port adaptor (circa 1990, drivers). Supports both coax and 10 Base-T.
Supplementary power is drawn from a passthrough cable. The. The Snappy Video SnapShot video capture device. and INTERSRV drive sharing utility. The audio deviceCurrent use For consumers, and 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 a 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 that provide interface to parallel port through network. USB-to-EPP chips can also allow other non-printer devices to continue to work on modern computers without 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. For parallel port connectors. Pin No (DB25)Pin No (36 pin)Signal nameDirectionRegister - bitInverted11StrobeIn/OutControl-0Yes22Data0OutData-0No33Data1OutData-1No44Data2OutData-2No55Data3OutData-3No66Data4OutData-4No77Data5OutData-5No88Data6OutData-6No99Data7OutData-7No1010AckInStatus-6No1111BusyInStatus-7Yes1212Paper-OutInStatus-5No1313SelectInStatus-4No1414LinefeedIn/OutControl-1Yes1532ErrorInStatus-3No1631ResetIn/OutControl-2No1736Select-PrinterIn/OutControl-3Yes18-2519-30,33,17,16Ground-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. – See also. which is sometimes called an 'Enhanced Parallel Port'., a Taiwanese computer component manufacturer partly known for having parallel port connectivity on their motherboardsHardware IC chips:.
For host computer, see. For peripheral side, parallel port interface chips: PPC34C60 (SMSC) and W91284PIC (Warp Nine). For USB-printer purpose, example USB chips: PL-2305 (Prolific) and CH341 (QinHeng)References. ^ James, Kevin. PC interfacing and data acquisition: techniques for measurement, instrumentation and control.
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