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
Chorded keyboard application ComboKey Plus enabling e.g. one-hand typing. The EkaPad is a 12-key chorded keyboard operated with the four fingers of one hand. It is supported on the thumb. With the 9 main keys, (operated by the index, middle, and ring fingers), 2 prefix keys and one delete key, the EkaPad can produce all the inputs of a standard qwerty keyboard with one, two, and a few three finger chords. For some characters one or two prefix chords are required. 9 main keys (3×3 matrix) can produce a total of 511 chords. With each of the three fingers limited to its