Until recently SIO was a relatively slow mode, but advances in silicon technology means that very fast SIO (hundreds of megabits per second) now make SIO a very cost-effective alternative to parallel interfaces. See USB, Firewire, serial IDE.
"serial input/output." A Dictionary of Computing. . Encyclopedia.com. (August 17, 2018). http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/serial-inputoutput
"serial input/output." A Dictionary of Computing. . Retrieved August 17, 2018 from Encyclopedia.com: http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/serial-inputoutput