Abstract: A computer system hating a digitizing tablet overlaying the display screen. The tablet serves as a user's primary input device. Various features of the system make it possible for the user to run and interact with standard programs designed for keystroke and mouse input and not designed for use with a tablet. In addition to the main processor, on which the user's programs are executed, there is an interface processor. In addition to a standard display buffer, there is an ink plane buffer for interface display data that is combined with the data from the standard display buffer on a pixel-by-pixel basis according to data from a mask plane buffer. The interface processor manages input from the tablet, presents feedback to the user by means of the ink and mask planes, and provides keystroke and mouse data to the main processor as if from a standard keyboard controller. The interface processor presents the user with a collection of simulated devices, including standard devices such as a keyboard and a mouse.

Abstract: A computer system having a digitizing tablet overlaying the display screen. The tablet serves as a user's primary input device. Various features of the system make it possible for the user to run and interact with standard programs designed for keystroke and mouse input and not designed for use with a tablet. In addition to the main processor, on which the user's programs are executed, there is an interface processor. In addition to a standard display buffer, there is an ink plane buffer for interface display data that is combined with the data from the standard display buffer on a pixel-by-pixel basis according to data from a mask plane buffer. The interface processor manages input from the tablet, presents feedback to the user by means of the ink and mask planes, and provides keystroke and mouse data to the main processor as if from a standard keyboard controller. The interface processor presents the user with a collection of simulated devices, including standard devices such as a keyboard and a mouse.

Abstract: A method and apparatus are described for processing a series of digital signals representing a stroke of a stylus on a tablet to remove signals at the ends of the stroke caused by retracing, the series of signals corresponding to the X and Y coordinates of a series of points along the direction of travel of the stroke. The signals for each point in the series are compared to the signals of the points adjacent to it to form a second series of signals which contain only those signals corresponding to points having an ordinate value more extreme than the corresponding ordinate value of its adjacent points. The first three points in the second series of signals are then processed to determine the ratio of the distance from the first point to the second point to the distance from the second point to the third point and to determine the size of the angle formed by the three points. The distance ratio is fed into a table-look-up which outputs a reference angle signal which is compared to the processed angle signal.

Abstract: An apparatus and method are disclosed for emulating computer keyboard input from a handprint terminal, the output of the handprint terminal comprising character data along with row and column position data for each character. A line buffer memory temporarily holds characters from the same row. While the characters belonging to any given row are stored in the line buffer memory, local editing may be performed to delete and/or add and/or change characters, with function signals being outputted from the apparatus by the control unit equivalent to function signals that would be outputted from a keyboard. When a character received is in a different row from the character preceeding it, the line buffer memory is cleared of all previous characters that had been loaded into it and carriage return or carriage-up signals are outputted from the control unit corresponding to the row change. The character is then loaded into the line buffer memory to start a new row.

Abstract: A method and apparatus are described for processing a series of digital signals representing a stroke of a stylus on a tablet to minimize noise at the ends of the stroke, the series of signals corresponding to the X and Y coordinates of a series of points along the direction of travel of the stroke. First the signals for the X and Y coordinates of each point in the series are compared to the signals for the X and Y coordinates of the points adjacent to it to form a second series of signals comprising only those signals having an ordinate value more extreme than the corresponding ordinate value of its adjacent points. The first point in the second series of signals is then compared with points succeeding the first point to identify the point in the second series that is furthest from the first point but within a predetermined distance from the first point. The point so located is identified as the end point at that end of the stroke.