Parallel port

Parallel port

A parallel port is a type of interface found on computers for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once, as opposed to serial interfaces that send bits one at a time.

Parallel port overview

The DB25 connector had an 8-bit data bus and a maximum cable length of 15-feet. Although there are 50 foot cables, it is not recommended that these cables be used as it can create poor connection and data signals. Below is additional information about each of the pins on this connector.25 PINs in parallel ports.

Below is an explanation of each of the above purposes.

Pin1 – Data acknowledgement when the signal is low.
Pin 2-9 – Data transfer pins.
Pin 10 – Acknowledge that the data has finished processing and when the signal is high indicates ready for more.
Pin 11 – When the signal goes high indicate that the printer has accepted the data and is processing it. Once this signal goes low and Pin 10 goes high will accept additional data.
Pin 12 – Printer paper jam when signal is high or no signal if printer jam.
Pin 13 – When high signal printer is indicating that it is on-line and ready to print.
Pin 14 – When low signal PC has indicated that the printer inset a line feed after each line.
Pin 15 – Printer sends data to the computer telling it that an error has occurred.
Pin 16 – When low signal PC has requested that the printer initiate an internal reset.
Pin 17 – When low signal the PC has selected the printer and should in return prepare for data being sent.
Pin 18-25 – Ground.


Used of parallel port

The parallel port has widely been replaced by the USB port. However, below is a listing of various hardware components that were used with the parallel port.

Printer – The most common use for the parallel port.

Scanner – Another commonly used parallel device is a parallel port scanner. Parallel port scanners are a popular alternative to SCSI scanners because of how easy they are to install.

External drives – Another popular use of the parallel ports are external drives such as the Iomega Zip drive, which can be removed from one computer and placed onto another.

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