The user generally applies _ to access mainframe or super computer.

Traditionally, user connect to a mainframe using a terminal which allowed them to input request to the mainframe. The mainframe would then handle all the computing before outputing a response. These terminals are called dumb terminals because they had no data-processing abilities of their own, they were simply windows through which users could access the mainframe. These days, terminal emulation software such as 3270 emulation is used in place of a terminal.