Editing Computer terminal (section)

===Graphical terminals{{anchor|Graphical terminal}}===
[[File:VT640-1.jpg|thumb|A normally text-only [[VT100]] terminal with a [[VT640]] conversion board displaying graphics]]
A '''graphical terminal''' can display images as well as text. Graphical terminals<ref>{{cite book |chapter=New Trends in Graphic Display System Architecture |first=E. M. |last=Kaya |title=Frontiers in Computer Graphics |pages=310–320 |date=1985|doi=10.1007/978-4-431-68025-3_23 |isbn=978-4-431-68027-7}}</ref> are divided into [[vector graphics|vector-mode]] terminals, and [[raster graphics|raster mode]].

A vector-mode display directly draws lines on the face of a [[cathode-ray tube]] under control of the host computer system. The lines are continuously formed, but since the speed of electronics is limited, the number of concurrent lines that can be displayed at one time is limited. Vector-mode displays were historically important but are no longer used.
Practically all modern graphic displays are raster-mode, descended from the picture scanning techniques used for [[television]], in which the visual elements are a rectangular array of [[pixel]]s. Since the raster image is only perceptible to the human eye as a whole for a very short time, the raster must be refreshed many times per second to give the appearance of a persistent display. The electronic demands of refreshing display memory meant that graphic terminals were developed much later than text terminals, and initially cost much more.<ref>{{cite journal |title=Using a Microprocessor in an Intelligent Graphics Terminal |quote=However, a major problem with the use of a graphic terminal is the cost|doi=10.1109/C-M.1976.218555 |year=1976 |last1=Raymond |first1=J. |last2=Banerji |first2=D.K. |journal=Computer |volume=9 |issue=4 |pages=18–25 |s2cid=6693597}}</ref><ref>{{cite journal |title=G101—A Remote Time Share Terminal with Graphic Output Capabilities |first=S. |last=Pardee
 |journal=[[IEEE Transactions on Computers]] |s2cid=27102280 |date=1971 |volume=C-20 |issue=8 |pages=878–881 |doi=10.1109/T-C.1971.223364 |quote=Terminal cost is currently about $10,000}}</ref>

Most terminals today{{when|date=June 2022}} are graphical; that is, they can show images on the screen. The modern term for graphical terminal is "[[thin client]]".{{Citation needed|date=June 2019}} A thin client typically uses a protocol such as X11 for Unix terminals, or [[Remote Desktop Protocol|RDP]] for Microsoft Windows. The bandwidth needed depends on the protocol used, the resolution, and the [[color depth]].

Modern graphic terminals allow display of images in color, and of text in varying sizes, colors, and [[font]]s (type faces).{{clarify|date=June 2022}}

In the early 1990s, an industry consortium attempted to define a standard, [[AlphaWindows]], that would allow a single CRT screen to implement multiple windows, each of which was to behave as a distinct terminal. Unfortunately, like [[I2O]], this suffered from being run as a closed standard: non-members were unable to obtain even minimal information and there was no realistic way a small company or independent developer could join the consortium.{{citation needed|date=January 2023}}