However, if one interlaced (flickering) desktop was displayed, all desktops onscreen would be similarly affected. The display chipset ('graphics card' on a PC) could switch between these desktop modes on the fly, and during the drawing of a single screen, usually with three pixel deep line between each desktop shown on the screen. Note: See for a list of reference material.Įach desktop or 'screen' could have its own colour depth (number of available colours) and resolution, including use of interlacing. The Copperlist did need to be sorted in vertical and horizontal wait position in order to function. A screen can move to any position, or display any portion, by modifying the wait, or fetch position. The video output is simply told (once, or many times) where to display (scanline) and from what screen memory address. This hardware-based scrolling does not use blitting, but something more like what is sometimes called hardware panning. Using the GUI implemented in system ROM API's, programs could transparently display multiple independent screens, from non-consecutive memory, without moving the memory. The Copper was a simple processor that could wait for a screen position and write to hardware registers. All Amigas supported multiple in-memory screens displayed concurrently via the use of the graphics co-processor, AKA the "Copper". The first platform to implement multiple desktop display as a hardware feature was Amiga 1000, released in 1985. Virtual desktop managers are available for most graphical user interface operating systems and offer various features, such as placing different wallpapers for each virtual desktop and use of hotkeys or other convenient methods to allow the user to switch amongst the different screens. The visible part of the larger virtual screen is called a viewport. The user can then scroll to them by moving the mouse pointer to the edge of the display.
For example, if a graphics card has a maximum resolution that is higher than the monitor's display resolution, the virtual desktop manager may allow windows to be placed "off the edge" of the screen. This facility is sometimes referred to as panning, scrolling desktops or view-port. Other kinds of virtual desktop environments do not offer discrete virtual screens, but instead make it possible to pan around a desktop that is larger than the available hardware is capable of displaying. Several X window managers provide switching desktops. A switching desktop provides a pager for the user to switch between "contexts", or pages of screen space, only one of which can be displayed on the computer's display at any given time. They are then only accessible to the user if that particular context is enabled. ("Virtual Desktop" was originally a trademark of Solbourne Computer.) Rather than simply being placed at an x, y position on the computer's display, windows of running applications are then placed at x, y positions on a given virtual desktop “context”. Switchable desktops were introduced to a much larger audience by Tom LaStrange in swm (the Solbourne Window Manager, for the X Window System) in 1989. Switchable desktops were designed and implemented at Xerox PARC as "Rooms" by Austin Henderson and Stuart Card in 1986 and (unknowingly to the authors until their publication) was conceptually similar to earlier work by Patrick Peter Chan in 1984.