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A fiber optic node has a broadband optical receiver, which converts the downstream optically modulated signal coming from the headend or hub to an electrical signal going to the customers. The fiber optic node also contains a reverse- or return-path transmitter that sends communication from customers back to the headend. 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. 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. Contention in a wireless or noisy spectrum, where the physical medium is entirely out of the control of those who specify the protocol, requires measures that also use up throughput. Companies were now fighting over who had the rights to physical access in communities. The connector has become so closely associated with Centronics that it is now popularly known as the "Centronics connector". IBM standardized the parallel cable with a DB25F connector on the PC side and the 36-pin Centronics connector on the printer side. IBM released the IBM Personal Computer in 1981 and included a variant of the Centronics interface- only IBM logo printers (rebranded from Epson) could be used with the IBM PC.

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 notable issue with the ATX specification was that it was last revised when power supplies were normally placed at the top of many old computer cases rather than at the bottom, as with many modern computer cases. As the electrical specification currently only defines a purpose for a single wire pair, some equipment manufacturers continue to use it. The printer side of the interface quickly became an industry de facto standard, but manufacturers used various connectors on the system side, so a variety of cables were required. The Dataproducts interface was found on many mainframe systems up through the 1990s, and many printer manufacturers offered the Dataproducts interface as an option. Dataproducts introduced a very different implementation of the parallel interface for their printers. 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). Cable operators have been gradually shifting to FTTP networks using PON (Passive Optical Networks). PhoneNet allowed AppleTalk networks to be connected together using normal telephone wires, and with very little extra work, could run analog phones and AppleTalk on a single four-conductor phone cable.

For consumers, USB and computer networks have replaced the parallel printer port, for connections both to printers and to other devices. A wide variety of devices were eventually designed to operate on a parallel port. The Enhanced Parallel Port (EPP), originally defined by Zenith Electronics, is similar to IBM's byte mode in concept, but changes details of the handshaking to allow up to 2 MB/s. Other changes in the handshaking protocols improved performance, reaching 400,000 cps to the printer, and about 50,000 cps back to the host. Government buildings were not inter-connected with telegraph lines, but relied on runners to carry messages back and forth. 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. New construction, additions or major modifications must follow the relevant code for that jurisdiction, which is not necessarily the latest version of the NEC. The US, however, continued to use American Morse code internally for some time, hence international messages required retransmission in both directions. ECP offers performance up to 2.5 MB/s in both directions.

The performance was defined by how rapidly the host could respond to the printer's BUSY signal asking for more data. 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. 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. 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). 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). While the IBM solution could support this, it was not trivial to implement and was not at that time being supported. 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.

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