Editing User interface (section)

=== 1969–present: Command-line user interface ===
{{main|Command-line interface}}

[[File:ASR-33 at CHM.agr.jpg|thumb|alt=Teletype Model 33|Teletype Model 33 ASR]]

'''Command-line interfaces''' ('''CLIs''') evolved from batch monitors connected to the system console. Their interaction model was a series of request-response transactions, with requests expressed as textual commands in a specialized vocabulary. Latency was far lower than for batch systems, dropping from days or hours to seconds. Accordingly, command-line systems allowed the user to change their mind about later stages of the transaction in response to real-time or near-real-time feedback on earlier results. Software could be exploratory and interactive in ways not possible before. But these interfaces still placed a relatively heavy [[mnemonic]] load on the user, requiring a serious investment of effort and learning time to master.<ref name="anaheimguide">{{cite web|title=HMI Guide|url=http://www.anaheimautomation.com/manuals/forms/hmi-guide.php#sthash.2McqS5xo.dpbs|url-status=live|archive-url=https://web.archive.org/web/20140620001341/http://www.anaheimautomation.com/manuals/forms/hmi-guide.php#sthash.2McqS5xo.dpbs|archive-date=2014-06-20}}</ref>

The earliest command-line systems combined [[teleprinter]]s with computers, adapting a mature technology that had proven effective for mediating the transfer of information over wires between human beings. Teleprinters had originally been invented as devices for automatic telegraph transmission and reception; they had a history going back to 1902 and had already become well-established in newsrooms and elsewhere by 1920. In reusing them, economy was certainly a consideration, but psychology and the [[Principle of least astonishment|rule of least surprise]] mattered as well; teleprinters provided a point of interface with the system that was familiar to many engineers and users.

[[File:DEC VT100 terminal.jpg|left|thumb|alt=The VT100, introduced in 197″8, was the most popular VDT of all time. Most terminal emulators still default to VT100 mode.|DEC VT100 terminal]]

The widespread adoption of video-display terminals (VDTs) in the mid-1970s ushered in the second phase of command-line systems. These cut latency further, because characters could be thrown on the phosphor dots of a screen more quickly than a printer head or carriage can move. They helped quell conservative resistance to interactive programming by cutting ink and paper consumables out of the cost picture, and were to the first TV generation of the late 1950s and 60s even more iconic and comfortable than teleprinters had been to the computer pioneers of the 1940s.

Just as importantly, the existence of an accessible screen—a two-dimensional display of text that could be rapidly and reversibly modified—made it economical for software designers to deploy interfaces that could be described as visual rather than textual. The pioneering applications of this kind were computer games and text editors; close descendants of some of the earliest specimens, such as [[Rogue (video game)|rogue]](6), and [[Vi (text editor)|vi]](1), are still a live part of [[Unix]] tradition.