The best replacement for serial is parallel.

The best alternatives to serial are rated as following:
★★★★★  parallel
★★  usb
★★  parallel processing
★  parallel port
★  episodic
★  series
★  ide
★  parallel communication
★  vga
★  ultra ata
★  serial
★  parallel ports
★  cereal
  parallel ata
  null modem
  parallel gpu water cooling
  parallel bus
  null modem cable
  keygen
  crack
  parallel buses
  parallel wiring
  parallel hard drive
  eide
  parallel communications
  parallel cable

Your alternative for serial is not listed? Suggest!
Speaking about serial, one probably shouldn't forget about shame.

Other search terms related to serial and their ratings are:
★★★★★ shame
★★★★★ idm
★★ putty
You have in mind a companion for serial and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of serial in all years. Click on graph for more.
serial
parallel
usb