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In computing, a parallel port is a type of interface found on early computers ... with 8 lines of data output and 4 lines of data input. [citation needed] ...
An IEEE 1284 36-pin female on a circuit board. In the 1970s, Centronics developed the now-familiar printer parallel port that soon became a de facto standard.Centronics had introduced the first successful low-cost seven-wire print head [citation needed], which used a series of solenoids to pull the individual metal pins to strike a ribbon and the paper.
Two two-port networks with input ports connected in parallel and output ports connected in series. When two-ports are connected in a parallel-series configuration as shown in figure 15, the best choice of two-port parameter is the g -parameters.
Creating a parallel port in a computer system is relatively simple, requiring only a latch to copy data onto a data bus. In contrast, most serial communication must first be converted back into parallel form by a universal asynchronous receiver/transmitter (UART) before they may be directly connected to a data bus.
For example, if port B and upper port C have to be initialized as input ports and lower port C and port A as output ports (all in mode 0): Since it is an I/O mode, D 7 = 1. Mode selection bits, D2, D5, D6 are all 0 for mode 0 operation. Port B and upper port C should operate as Input ports, hence, D 1 = D 3 = 1.
The LapLink cable connects five output pins of a parallel port to five input pins on the opposing port for each direction. Due to the lack of internal timing in the parallel ports, synchronization is implemented via software handshaking: four pins are used for data transfer and one is used for synchronization.
Parallel I/O, in the context of a computer, means the performance of multiple input/output operations at the same time, for instance simultaneously outputs to storage devices and display devices. [1] It is a fundamental feature of operating systems .
In general, parallel interfaces are quoted in B/s and serial in bit/s. The more commonly used is shown below in bold type. On devices like modems, bytes may be more than 8 bits long because they may be individually padded out with additional start and stop bits; the figures below will reflect this.