HCI is a branch of the science of ergonomics, and is concerned especially with the relationship between workstations and their operators. The aim is to develop acceptable standards for such aspects as display resolution, use of color, and navigation around an application.
The terms human-system interface (HSI), human-machine interface (HMI), and man-machine interface (MMI) are all used as synonyms.
"human-computer interface." A Dictionary of Computing. . Encyclopedia.com. (August 9, 2018). http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/human-computer-interface
"human-computer interface." A Dictionary of Computing. . Retrieved August 09, 2018 from Encyclopedia.com: http://www.encyclopedia.com/computing/dictionaries-thesauruses-pictures-and-press-releases/human-computer-interface