The best replacement for parallel port is serial port.

The best alternatives to parallel port are rated as following:
★★★★★  serial port
★  usb port
  printer port
  serial

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Speaking about parallel port, one probably shouldn't forget about labview.

Other search terms related to parallel port and their ratings are:
★★★★★ labview
★ led
8255
You have in mind a companion for parallel port and it is not yet here? Propose!



Google Trends

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parallel port
serial port
usb port