Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Reactivity was a major goal in the early user interface research at MIT and Xerox PARC. A computer program which was not reactive would not be considered user friendly no matter how elaborate its presentation. Early word-processing programs whose on-screen representations look noth ...Full description
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Reactivity was a major goal in the early user interface research at MIT and Xerox PARC. A computer program which was not reactive would not be considered user friendly no matter how elaborate its presentation. Early word-processing programs whose on-screen representations look nothing like their printer output could be reactive. The common example was WordStar on CP/M. On-screen, it looked like a markup language in a character cell display, but it had deep built-in help which was always available from an on-screen menu bar, and the effect of each keystroke was obvious.