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
Keyboard layout The visual layout of any keyboard can also be changed by simply replacing its keys or attaching labels to them, such as to change an English-language keyboard from the common QWERTY to the Dvorak layout, although for touch typists, the placement of the tactile bumps on the home keys is of more practical importance than that of the visual markings. In the past, complex software that mapped many non-standard functions to the keys (such as a flight simulator) would be shipped with a "keyboard overlay", a large sheet of paper with pre-cut holes matching the key layout of a particular