Control-C else, typically returning control to the user. Ctrl-C was one of a handful of keyboard sequences chosen by the program designers at Xerox PARC to control text editing, with Ctrl-Z (Undo), Ctrl-X (Cut), Ctrl-V (Paste), and Ctrl-P (Print). The first four letters are all located together at the left end of the bottom row of the standard QWERTY keyboard, and P towards the upper right. The equivalent key combination on Macintosh computers is Command-C. Control-C as an abort command was popularized by TOPS-20 and TOPS-10 and adopted by other systems including Unix. It was also adopted by Digital Equipment operating
Optimus Maximus keyboard when the user presses the shift key, the pictures would change to upper-case versions. It would also make switching between different keyboard layouts (such as English and Cyrillic) rapid, and could make the switch to alternative layouts such as Dvorak easier for people who only have a QWERTY keyboard with no possibility of rearranging the keys. To demonstrate this concept, there are computer renderings showing example layouts for "Quake III Arena" and Adobe Photoshop. A patent application filed on March 13, 2007 suggests that Apple Inc. may be working on a similar dynamically changeable organic light-emitting diode (OLED) keyboard. Art.